Video data processing apparatus, video data encoding apparatus, and methods thereof

ABSTRACT

A pattern analyzing portion analyzes a pattern of a detected repeat field and determines whether or not the pattern of the repeat field is continuous. An inverse pull-down controlling portion controls a memory to read video data in such a manner that the repeat field detected by a comparator is removed from input video data in a period that the pattern of the repeat field is continuous. The inverse pull-down controlling portion controls the memory to read video data in such a manner that a repeat field detected by the comparator is not removed from the input video data in a period that the pattern of the repeat field is discontinuous. In other words, an inverse 2:3 pull-down process is controlled corresponding to the continuity of a pattern of a repeat field. In addition, it is determined whether an input original material is a progressive-scanned video material or an interlace-scanned video material corresponding to the continuity of the pattern of the repetitive material.

TECHNICAL FIELD

[0001] The present invention relates to a video data processingapparatus and a method thereof for performing an inverse 2:3 pull-downprocess for a television signal of which a film material has beenprocessed with 2:3 pull-down process so as to remove redundant fields.In addition, the present invention relates to a video data encodingapparatus and a method thereof for effectively compression-encodingvideo data that has been processed with the inverse 2:3 pull-downprocess.

BACKGROUND ART

[0002] A telecine unit that converts a film material recorded on anoptical film for a movie and so forth into a television signal has beenproposed. Generally, on a film material that is used for a movietheater, pictures have been recorded at a frame rate of 24 Hz (24 framesper second). Thus, the frame rate of a film material is completelydifferent from that of an NTSC format television signal at a frame rateof 29.97 Hz. Thus, in the telecine unit, a process for converting 24frames into 30 frames is performed. In such a process, two fields of anoriginal film material are converted into three fields in apredetermined sequence. Thus, such a process is referred to as 2:3pull-down process. In reality, a particular field of an original filmmaterial is repeated in a predetermined sequence. The repeated field isinserted between fields of the original film material (hereinafter, therepeated field is referred to as repeat field). Thus, with the filmmaterial at a frame rate of 24 Hz, a television signal at a frame rateof 30 Hz is generated.

[0003] Video data converted into a television signal by the telecineunit is compression-encoded by a compression-encoding technique such asMPEG encoding method. The encoded video stream is recorded on a recordmedium or transmitted to a transmission medium. Before video data thathas been processed with the 2:3 pull-down process iscompression-encoded, the repeat fields are removed so as to improve thecompression-encoding efficiency. This is because the repeat fields areredundant fields that have been added with the 2:3 pull-down process.Thus, even if these repeat fields are removed, the picture quality doesnot deteriorate. A process for removing redundant fields added with the2:3 pull-down process is referred to as inverse 2:3 pull-down process.

[0004] To remove repeat fields in the inverse 2:3 pull-down process, therepeat fields should be detected. To detect repeat fields, a simplealgorithm is used. In the algorithm, the luminance difference betweentwo fields (first and second fields) is calculated. When the luminancedifference is almost “0”, it is determined that the second field is arepeat field.

[0005] However, since video data that has been processed with the 2:3pull-down process is data of which a material optically recorded on anoptical film is converted into a television data, the video datacontains noise due to a miss-alignment of the film or dust and stainthereof. Thus, when video data that has been processed with the 2:3pull-down process is processed with the inverse 2:3 pull-down process bya conventional repeat field detecting algorithm, if noise contained inthe video data is small, repeat fields can be accurately detected.However, if noise contained in the video data is very large, normalfields (=not repeat fields) may be incorrectly determined as repeatfields.

[0006] In a broadcasting station, a video program production company,and so forth, video data generated from film material is not transmittedwithout editing process as a television program. Instead, a televisionprogram is generated by inserting new video data such as commercialprogram in the video data generated from film material by video editingprocess. The new video data is not video data generated from a filmmaterial, but video data (with a frame frequency of 29.97 Hz) that hasbeen shot by a video camera or the like. In other words, the editedvideo program is including both video data generated from a filmmaterial by the 2:3 pull-down process (the frame frequency of theoriginal material is 24 Hz) and normal video data (the frame frequencyof the original material is 29.97 Hz).

[0007] When the inverse 2:3 pull-down process is performed for theedited video program using the above-described repeat field detectingalgorithm, as long as the above-described noise is not abnormally large,repeat fields are removed from the video data generated from the filmmaterial. However, when the inverse 2:3 pull-down process is performedusing the repeat field detecting algorithm, normal fields may bedetected as repeat fields. When new inserted video data is similar to astill picture rather than moving picture, the probability of whichnormal fields are incorrectly detected as repeat fields becomes high.

[0008] In other words, in the conventional inverse 2:3 pull-downprocess, normal fields may be incorrectly detected as repeat fields.Thus, in the conventional inverse 2:3 pull-down process, repeat fieldscannot be accurately removed. When normal fields are determined asrepeat fields, the normal fields are removed from video data that hasbeen processed with the inverse 2:3 pull-down process. As a result,field drop-outing of the normal field may occur.

[0009] Unlike with a storage system that records a supplied sourcematerial to a storage medium, in a digital broadcasting system, a sourcematerial should be processed and transmitted to individual subscriberson real time basis. Moreover, in the digital broadcasting system, thefield drop-outing should be avoided from taking place in video data. Inother words, in the digital broadcasting system, video data free ofunnatural motion should be transmitted as an essential condition. Therequirement of video data free of unnatural motion is superior to therequirement of the transmission efficiency using the inverse 2:3pull-down process.

[0010] Thus, in a conventional digital broadcasting system, tocompletely prevent the field drop-outing from taking place intransmission video data, the inverse 2:3 pull-down process has not beenperformed at all. Consequently, the compression efficiency deterioratesby around 25% in comparison with the case that repeat fields are fullyremoved.

DISCLOSURE OF THE INVENTION

[0011] Therefore, an object of the present invention is to provide avideo data processing apparatus and a video data processing method forperforming an inverse 2:3 pull-down process for video data that has beenprocessed with a 2:3 pull-down process in the case that video datagenerated from a film material is compression-encoded and broadcast freefrom a frame skip due to an incorrect detection of a repeat field.

[0012] Another object of the present invention is to provide a videodata encoding apparatus and a video data encoding method for performingthe above-described inverse 2:3 pull-down process and for performing acompression-encoding process for video data with high compressionefficiency.

[0013] To accomplish the above object, claim 1 of the present inventionis a video data processing apparatus for removing a repeat field fromvideo data, comprising a repeat field detecting means for detecting therepeat field contained in the video data, an analyzing means foranalyzing a pattern of the repeat field contained in the video datacorresponding to the detected results of the repeat field detectingmeans and determining whether the pattern of the repeat field iscontinuous or discontinuous, a video data processing means for removingthe repeat field contained in the video data, and a controlling meansfor controlling the video data processing means to remove a fielddetermined as a repeat field by the repeat field detecting means fromthe video data in a period that the patten of the repeat field isdetermined continuous by the analyzing means and for controlling thevideo data processing means not to remove a field determined as a repeatfield by the repeat field detecting means from the video data in aperiod that the pattern of the repeat field is determined discontinuousby the analyzing means.

[0014] Claim 12 of the present invention is a video data processingapparatus for removing a repeat field from video data, comprising arepeat field detecting means for detecting the repeat field contained inthe video data, an analyzing means for determining whether or not anoccurrence sequence of the repeat field contained in the video data isregular corresponding to the detected results of the repeat fielddetecting means, a video data processing means for removing the repeatfield contained in the video data, and a controlling means forcontrolling the video data processing means to remove a field determinedas a repeat field by the repeat field detecting means from the videodata in a period that the occurrence sequence of the repeat field isdetermined regular by the analyzing means and for controlling the videodata processing means not to remove a field determined as a repeat fieldby the repeat field detecting means from the video data in a period thatthe occurrence sequence of the repeat field is determined irregular bythe analyzing means.

[0015] Claim 13 of the present invention is a video data processingapparatus for processing video data of which a first video material ofwhich an original material is processed with 2 3 pull-down process and asecond video material of an original material with a frequency of anormal television signal coexist, comprising an analyzing means foranalyzing a repetitive pattern of the repeat field contained in thevideo data and determining whether a current field of the video data isa field of the first video material or a field of the second videomaterial, a video data processing means for removing the repeat fieldfrom the video data, and a controlling means for controlling theoperation of the video data processing means corresponding to theanalyzed results of the analyzing means.

[0016] Claim 22 of the present invention is a video data processingapparatus for processing video data field by field, aprogressive-scanned video material and an interlace-scanned videomaterial coexisting in the video data, comprising an analyzing means foranalyzing the continuity of a repeat field contained in the video dataand determining whether the current field of the video data is a fieldof the progressive-scanned video material or a field of theinterlace-scanned video material, a video data processing means forremoving the repeat field from the video data, and a controlling meansfor controlling the video data processing means to remove a repeat fieldcontained in the progressive-scanned video material and not to remove afield contained in the interlace-scanned video material corresponding tothe analyzed results of the repeat field analyzing means.

[0017] Claim 23 of the present invention is a video data processingmethod for removing a repeat field from video data, comprising the stepsof detecting the repeat field contained in the video data, analyzing apattern of the repeat field contained in the video data corresponding tothe detected results of the repeat field detecting step and determiningwhether the pattern of the repeat field is continuous or discontinuous,removing the repeat field contained in the video data, and controllingthe video data processing step to remove a field determined as a repeatfield by the repeat field detecting step from the video data in a periodthat the patten of the repeat field is determined continuous by theanalyzing step and the video data processing step not to remove a fielddetermined as a repeat field by the repeat field detecting step from thevideo data in a period that the pattern of the repeat field isdetermined discontinuous by the analyzing step.

[0018] Claim 34 of the present invention is a video data processingmethod for removing a repeat field from video data, comprising the stepsof detecting the repeat field contained in the video data, determiningwhether or not an occurrence sequence of the repeat field contained inthe video data is regular corresponding to the detected results of therepeat field detecting step, removing the repeat field contained in thevideo data, and controlling the video data processing step to remove afield determined as a repeat field by the repeat field detecting stepfrom the video data in a period that the occurrence sequence of therepeat field is determined regular by the analyzing step and the videodata processing step not to remove a field determined as a repeat fieldby the repeat field detecting step from the video data in a period thatthe occurrence sequence of the repeat field is determined irregular bythe analyzing step.

[0019] Claim 35 of the present invention is a video data processingmethod for processing video data of which a first video material ofwhich an original material is processed with 2 3 pull-down process and asecond video material of an original material with a frequency of anormal television signal coexist, comprising the steps of analyzing arepetitive pattern of the repeat field contained in the video data anddetermining whether a current field of the video data is a field of thefirst video material or a field of the second video material, removingthe repeat field from the video data, and controlling the operation ofthe video data processing means corresponding to the analyzed results ofthe analyzing step.

[0020] Claim 44 of the present invention is a video data processingmethod for processing video data field by field, a progressive-scannedvideo material and an interlace-scanned video material coexisting in thevideo data, comprising the steps of analyzing the continuity of a repeatfield contained in the video data and determining whether the currentfield of the video data is a field of the progressive-scanned videomaterial or a field of the interlace-scanned video material, removingthe repeat field from the video data, and controlling the video dataprocessing step to remove a repeat field contained in theprogressive-scanned video material and not to remove a field containedin the interlace-scanned video material corresponding to the analyzedresults of the repeat field analyzing step.

[0021] Claim 45 of the present invention is a video data encodingapparatus for encoding video data in which a repeat field is placed in apredetermined sequence, comprising, an analyzing means for analyzing apattern of the repeat field contained in the video data and determiningwhether or not the pattern of the repeat field is continuous, a videodata processing means for removing the repeat field from the video data,an encoding means for encoding video data that is output from the videodata processing means, and a controlling means for controlling the videodata processing means to remove a field determined as a repeat field bythe repeat field detecting means and perform an encoding process in aframe prediction mode and a frame DCT mode in a period that the patternof the repeat field is determined continuous by the analyzing means andfor controlling the video processing means not to remove a fielddetermined as a repeat field by the repeat field detecting means andperform an encoding process in one of a frame prediction mode and afield prediction mode and one of a frame DCT mode and a field DCT modein a period that the pattern of the repeat field is determineddiscontinuous by the analyzing means.

[0022] Claim 46 of the present invention is a video data encodingapparatus for encoding video data of which a first video material ofwhich an original material is processed with 2:3 pull-down process and asecond video material of an original material with a frequency of anormal television signal coexist, comprising an analyzing means foranalyzing a repetitive pattern of the repeat field contained in thevideo data and determining whether the current field of the video datais a field of the first video material or a field of the second videomaterial, a video data processing means for removing the repeat fieldfrom the video data, an encoding means for encoding video data that isoutput from the video data processing means, and a controlling means forcontrolling an operation of the video data processing means and anencoding mode of the encoding means corresponding to the analyzedresults of the analyzing means.

[0023] Claim 47 of the present invention is a video data encodingapparatus for encoding video data of which a progressive-scanned videomaterial and an interlace-scanned video material coexist, comprising ananalyzing means for analyzing the continuity of a repeat field containedin the video data and determining whether the video data is theprogressive-scanned video data or the interlace-scanned video data, avideo data processing means for removing the repeat field from the videodata, an encoding means for encoding video data that is output from thevideo data processing means, and a controlling means for controlling thevideo data processing means to remove a repeat field contained in theprogressive-scanned video material and not to remove a field containedin the interlace-scanned video material corresponding to the analyzedresults of the analyzing means and for controlling the encoding means toselect an encoding mode corresponding to the progressive-scanned videomaterial or the interlace-scanned video material.

[0024] Claim 48 of the present invention is a video data encodingapparatus for encoding video data of which a progressive-scanned videomaterial and an interlace-scanned video material coexist, comprising ananalyzing means for analyzing the continuity of a repeat field containedin the video data and determining whether the video data is theprogressive-scanned video data or the interlace-scanned video data, avideo data processing means for removing the repeat field from the videodata, an encoding means for encoding video data that is output from thevideo data processing means, and a controlling means for controlling thevideo data processing means to remove a repeat field contained in thevideo data and the encoding means to perform an encoding process in anencoding mode corresponding to the progressive-scanned video materialwhen the video data is determined as the progressive-scanned videomaterial by the analyzing means and for controlling the video dataprocessing means not to remove a repeat field contained in the videodata and the encoding means to perform an encoding process in anencoding mode corresponding to the interlace-scanned video material whenthe video data is determined as the interlace-scanned video material bythe analyzing means.

[0025] Claim 49 of the present invention is a video data encodingapparatus for encoding video data in which a repeat field is placed,comprising a video data processing means for removing the repeat fieldfrom the video data, an encoding means for encoding video data that hasbeen processed by the video data processing means, and a controllingmeans for analyzing the continuity of a repeat field contained in thevideo data, determining whether a pattern of the repeat field containedin the video data is continuous or discontinuous, and controlling anoperation of the video data processing means and an encoding mode of theencoding means.

[0026] Claim 50 of the present invention is a video data encodingapparatus for encoding video data in which a repeat field is placed,comprising a video data processing means for removing the repeat fieldfrom the video data, an encoding means for encoding video data that hasbeen processed by the video data processing means, and a controllingmeans for analyzing the continuity of a repeat field contained in thevideo data, determining whether an original material of the video datais a progress-scanned video material or interlace-scanned video data,and controlling an operation of the video data processing means and anencoding mode of the encoding means.

[0027] Claim 51 of the present invention is a video data encoding methodfor encoding video data in which a repeat field is placed in apredetermined sequence, comprising the steps of analyzing a pattern ofthe repeat field contained in the video data and determining whether ornot the pattern of the repeat field is continuous, removing the repeatfield from the video data, encoding video data that is output from thevideo data processing step, and controlling the video data processingstep to remove a field determined as a repeat field by the repeat fielddetecting step and perform an encoding process in a frame predictionmode and a frame DCT mode in a period that the pattern of the repeatfield is determined continuous by the analyzing step and for controllingthe video processing step not to remove a field determined as a repeatfield by the repeat field detecting step and perform an encoding processin one of a frame prediction mode and a field prediction mode and one ofa frame DCT mode and a field DCT mode in a period that the pattern ofthe repeat field is determined discontinuous by the analyzing step.

[0028] Claim 52 of the present invention is a video data encoding methodfor encoding video data of which a first video material of which anoriginal material is processed with 2 3 pull-down process and a secondvideo material of an original material with a frequency of a normaltelevision signal coexist, comprising the steps of analyzing arepetitive pattern of the repeat field contained in the video data anddetermining whether the current field of the video data is a field ofthe first video material or a field of the second video material,removing the repeat field from the video data, encoding video data thatis output from the video data processing step, and controlling anoperation of the video data processing step and an encoding mode of theencoding step corresponding to the analyzed results of the analyzingstep.

[0029] Claim 53 of the present invention is a video data encoding methodfor encoding video data of which a progressive-scanned video materialand an interlace-scanned video material coexist, comprising the steps ofanalyzing the continuity of a repeat field contained in the video dataand determining whether the video data is the progressive-scanned videodata or the interlace-scanned video data, removing the repeat field fromthe video data, encoding video data that is output from the video dataprocessing step, and controlling the video data processing step toremove a repeat field contained in the progressive-scanned videomaterial and not to remove a field contained in the interlace-scannedvideo material corresponding to the analyzed results of the analyzingstep and for controlling the encoding step to select an encoding modecorresponding to the progressive-scanned video material or theinterlace-scanned video material.

[0030] Claim 54 of the present invention is a video data encoding methodfor encoding video data of which a progressive-scanned video materialand an interlace-scanned video material coexist, comprising the steps ofanalyzing the continuity of a repeat field contained in the video dataand determining whether the video data is the progressive-scanned videodata or the interlace-scanned video data, removing the repeat field fromthe video data, encoding step for encoding video data that is outputfrom the video data processing step, and controlling the video dataprocessing step to remove a repeat field contained in the video data andthe encoding step to perform an encoding process in an encoding modecorresponding to the progressive-scanned video material when the videodata is determined as the progressive-scanned video material by theanalyzing step and for controlling the video data processing step not toremove a repeat field contained in the video data and the encoding stepto perform an encoding process in an encoding mode corresponding to theinterlace-scanned video material when the video data is determined asthe interlace-scanned video material by the analyzing step.

[0031] Claim 55 of the present invention is a video data encoding methodfor encoding video data in which a repeat field is placed, comprisingthe steps of removing the repeat field from the video data, encodingvideo data that has been processed by the video data processing step,and analyzing the continuity of a repeat field contained in the videodata, determining whether a pattern of the repeat field contained in thevideo data is continuous or discontinuous, and controlling an operationof the video data processing step and an encoding mode of the encodingstep.

[0032] Claim 56 of the present invention is a video data encoding methodfor encoding video data in which a repeat field is placed, comprisingthe steps of removing the repeat field from the video data, encodingvideo data that has been processed by the video data processing step,and analyzing the continuity of a repeat field contained in the videodata, determining whether an original material of the video data is aprogress-scanned video material or interlace-scanned video data, andcontrolling an operation of the video data processing step and anencoding mode of the encoding step.

BRIEF DESCRIPTION OF DRAWINGS

[0033]FIGS. 1A and 1B are schematic diagrams showing a 2:3 pull-downprocess;

[0034]FIG. 2 is a block diagram showing a fundamental structure of avideo data processing apparatus performing an inverse 2:3 pull-downprocess;

[0035]FIG. 3 is a schematic diagram showing video data that is processedwith the 2:3 pull-down process and input to the video data processingapparatus;

[0036]FIG. 4 is a schematic diagram showing a difference valuecalculating process of a luminance signal in a luminance differencecalculating portion;

[0037]FIG. 5 is a schematic diagram showing video data that is processedwith the 2:3 pull-down process and input to the video data processingapparatus;

[0038]FIG. 6 is a schematic diagram showing an example of data stored ina FIFO register in the case that repetitive patterns are detected;

[0039]FIGS. 7A and 7B are schematic diagrams showing the results of arepeat field detecting process of a comparator;

[0040]FIGS. 8A and 8B are schematic diagrams showing results of therepeat field detecting process of the comparator;

[0041]FIG. 9 is a schematic diagram showing a state transitioncorresponding to a pattern;

[0042]FIG. 10 is a schematic diagram showing a pattern analyzing processperformed by a pattern analyzing portion;

[0043]FIG. 11 is a block diagram showing the structure of an example ofa video encoding portion corresponding to MPEG standard;

[0044]FIGS. 12A and 12B are schematic diagrams showing macroblockstructures; and

[0045]FIGS. 13A and 13B are schematic diagrams showing macroblockscorresponding to DCT modes.

BEST MODE FOR CARRYING OUT THE INVENTION

[0046] For easy understanding of the concept of the present invention,with reference to FIG. 1, a process for converting a film material of 25frames per second into an NTSC format television material of 30 framesper second (accurately, 29.97 frames per second) will be described. Thisprocess is referred to as 2:3 pull-down process. The film material has24 frames per second. The same pictures of two fields (a top field and abottom field) are formed with each frame. Thus, a picture signal of 48fields per second is generated. Next, four frames (eight fields) of thefilm material are converted into for example an NTSC format video signalof five frames (10 fields). In FIG. 1A, reference letters A, B, C, and Drepresent-top fields of the film material and reference letters a, b, c,and d represent bottom fields of the film material.

[0047] In the 2:3 pull-down process, particular fields (for example, Aand c) of the film material are repetitively placed so as to increasethe number of fields.

[0048] In the inverse 2:3 pull-down process, video data of repeat fieldsplaced as shown in FIG. 1B is removed from video data at a frame rate of30 frames per second. Thus, the video data at a frame rate of 30 framesper second is converted into video data at a frame rate of 24 frames parsecond as shown in FIG. 1A.

[0049] Next, with reference to FIG. 2, the structure of the video dataprocessing apparatus according to an embodiment of the present inventionwill be described. The video data processing apparatus comprises aninverse pull-down processing portion 10, a video encoding portion 20,and a video data transmitting portion 30.

[0050] The inverse pull-down processing portion 10 is a block thatperforms the inverse 2:3 pull-down process for video data VIN of atelevision program generated from a film material by the 2:3 pull-downprocess. The video encoding portion 20 is a block that encodes the videodata that has been processed with the inverse pull-down processcorresponding to MPEG technology. The video data transmitting portion 30is a block that converts an encoded video stream into a format for atransmission to subscribers and a format for a storage medium.

[0051] Next, the structures of the inverse pull-down processing portion10 and the video encoding portion 20 will be described.

[0052] The inverse pull-down processing portion 10 comprises an addressmanaging portion 100, a memory 102, a luminance difference calculatingportion 104, a difference value register 106, a comparator 108, apattern analyzing portion 110, a FIFO register 112, an inverse pull-downcontrolling portion 114, a first threshold value register 116, a secondthreshold value register 118, a switch circuit 120, and an addressmanaging portion 122.

[0053]FIG. 3 shows an example of a field structure of input video dataVIN that is supplied from a telecine unit that performs the 2:3pull-down process or a VTR unit that stores video data that has beenprocessed with the 2:3 pull-down process to the inverse pull-downprocessing portion 10. In the example shown in FIG. 3, the video dataVIN is (4:2:2) video data.

[0054] The address managing portion 100 generates a write address of thememory 102 for the input video data VIN for each field and supplies thegenerated write address to the memory 102. In addition, the addressmanaging portion 100 supplies the write address of the memory 102 forthe input video data VIN to the inverse pull-down controlling portion114.

[0055] As shown in FIG. 3, the memory 102 buffers the source video dataVIN for each field corresponding to the write address received from theaddress managing portion 100. In addition, the memory 102 reads videodata corresponding to the read address received from the addressmanaging portion 122 and outputs the video data as video data VOUT thathas been processed with the inverse 2:3 pull-down process to the videoencoding portion 20.

[0056] The luminance difference calculating portion 104 receives theinput video data VIN for each field from the memory 102 and obtains thedifference between two fields of the input video data VIN (hereinafter,the difference between fields is referred to as difference value). Inreality, the luminance difference calculating portion 104 calculates thedifference value between top fields with the difference betweenluminance components of two temporally continuous top fields. Inaddition, the luminance difference calculating portion 104 calculatesthe difference value between bottom fields with the difference betweenluminance components of two temporarily continuous bottom fields. Thedifference value is obtained by summing the absolute value of thedifference between the luminance of pixels at the same positions on topfields (or bottom fields) of two temporally continuous frames for eachpixel of one screen. The difference value may be obtained by summing thesquare of the difference between each pixel value. As anotheralternative method, instead of summing all pixels of one screen, theabsolute value of the difference between each pixel value that is largerthan a predetermined threshold value may be summed. As a furtheralternative method, the difference value may be obtained using colorcomponents along with luminance components of each pixel.

[0057]FIG. 4 is a schematic diagram showing a difference valuecalculating process performed by the luminance difference calculatingportion 104 for a luminance signal. As shown in FIG. 4, the luminancedifference calculating portion 10 successively calculates the differencevalues (|A−B|˜|D−E| . . . ) between two continuous top fields and thedifference values (|a−b|˜|d−e| . . . ) between two continuous bottomfields. The calculated difference values are output to the differencevalue register 106.

[0058] The difference value register 106 is a register that stores thedifference values for 10 frames (20 fields) received from the luminancedifference calculating portion 104.

[0059] The comparator 108 is a circuit that determines whether or noteach field is a repeat field. When the comparator 108 determines whetheror not a top field “C” shown in FIG. 5 is a repeat field, the comparator108 calculates the following formula (1) with the difference values(|A−B|˜|D−E| . . . ) stored in the difference value register 106 and athreshold value “T” received from the switch circuit 120.$\begin{matrix}\begin{matrix}\begin{matrix}\begin{matrix}\begin{matrix}{{{B - C}} \approx 0} \\{AND}\end{matrix} \\{{{{A - B}} - {{B - C}}} > T}\end{matrix} \\{AND}\end{matrix} \\{{{{C - D}} - {{B - C}}} > T}\end{matrix} & (1)\end{matrix}$

[0060] When the conditions of the formula (1) are satisfied, thecomparator 108 determines that the top field “C” is a repeat field. Whenthe conditions of the formula (1) are not satisfied, the comparator 108determines that the top field “C” is not a repeat field. The comparator108 performs the repeat field determining process using the formula (1)for all top fields.

[0061] Likewise, when the comparator 108 determines whether or not abottom field e shown in FIG. 5 is a repeat field, the comparator 108calculates the following formula (2) with the difference values(|a−b|˜|d−e| . . . ) and the threshold value T received from the switchcircuit 120. $\begin{matrix}\begin{matrix}\begin{matrix}\begin{matrix}\begin{matrix}{{{d - e}} \approx 0} \\{AND}\end{matrix} \\{{{{c - d}} - {{d - e}}} > T}\end{matrix} \\{AND}\end{matrix} \\{{{{e - f}} - {{d - e}}} > T}\end{matrix} & (2)\end{matrix}$

[0062] When the conditions of the formula (2) are satisfied, thecomparator 108 determines that the bottom field e is a repeat field.When the conditions of the formula (2) are not satisfied, the comparator108 determines that the bottom field e is not a repeat field. Thecomparator 108 performs the repeat field determining process using theformula (2) for all bottom fields.

[0063] Next, the theory of the repeat field determining process of thecomparator 108 corresponding to the formulas (1) and (2) will bedescribed. As described above, the repeat field C is a repeat field ofthe top field B in the 2:3 pull-down process. The repeat field e is arepeat field of-the bottom field d in the 2:3 pull-down process. Thus,the field C almost matches the field B. The field e almost matches thefield d. Thus, each of the difference value |B−C| and the differencevalue |d−e| of temporally adjacent fields is almost 0. However, due tonoise in the 2:3 pull-down process, each of the difference values is notexactly 0.

[0064] When a reference top field satisfies the conditions of theformula (1), the comparator 108 outputs a flag “1” that represents thatthe reference field is a repeat field to the pattern analyzing portion110. When the reference top field does not satisfy the conditions of theformula (1), the comparator 108 outputs a flag “0” that represents thatthe reference field is a normal field to the pattern analyzing portion110. Likewise, when the reference bottom field satisfies the conditionsof the formula (2), the comparator 108 outputs a flag “1” thatrepresents the reference bottom field is a repeat field to the patternanalyzing portion 110. When the reference bottom field does not satisfythe conditions of the formula (2), the comparator 108 outputs a flag “0”that represents that the reference bottom field is a normal field to thepattern analyzing portion 110.

[0065] The pattern analyzing portion 110 is a circuit that analyzeswhether or not patterns of repeat fields of the input video data VIN arecontinuous. When the patterns are continuous, it means that theoccurrence sequence of the repeat fields of the input video data VIN isregular. On the other hand, when the patterns are discontinuous, itmeans that the occurrence sequence of repeat fields of the input videodata VIN is irregular or that repeat fields are not contained in theinput video data VIN.

[0066] The pattern analyzing portion 110 receives a flag “1” thatrepresents a repeat field and a flag “0” that represents a normal fieldfrom the comparator 108 and stores the received flag data to the FIFOregister 112.

[0067] The FIFO register 112 stores the latest flags for two seconds(for 120 fields). When the pattern analyzing portion 110 detectsrepetitive patterns shown in FIG. 5, data shown in FIG. 6 is stored inthe FIFO register 112. Data stored in the FIFO register 112 is updatedfor each field under the control of the pattern analyzing portion 110.Thus, the FIFO register 112 usually stores 120 flags corresponding tothe latest 120 fields.

[0068] The pattern analyzing portion 110 searches 120 flags stored inthe FIFO register 112 and determines whether or not patterns of repeatfields of the input video data VIN are continuous based on apredetermined pattern detecting algorithm. When the patterns of therepeat fields of the input video data are continuous, the patternanalyzing portion 110 supplies a continuity flag “1” that representsthat the patterns are continuous to the inverse pull-down controllingportion 114. When the patterns of the repeat fields of the input videodata are discontinuous, the pattern analyzing portion 110 supplies acontinuity flag “0” that represents that the patterns are discontinuousto the inverse pull-down controlling portion 114.

[0069] Next, with reference to FIGS. 7 to 10, the pattern detectingalgorithm will be described in detail.

[0070]FIGS. 7 and 8 show results of the repeat field detecting processof the comparator 108. In FIGS. 7 and 8, black circles represent repeatfields determined by the comparator 108 and white circles representnormal fields determined by the comparator 108. FIGS. 7A and 8A showexamples of which patterns of repeat fields of the input video data VINare continuous. FIGS. 7B and 8B show two examples of which patterns ofrepeat fields of the input video data VIN are discontinuous.

[0071] Since the 2:3 pull-down process is a process for inserting repeatfields in a regular sequence, when the repeat field detecting process isperformed for video data that has been processed with the 2:3 pull-downprocess, patterns as shown in FIGS. 7A and 8A are obtained. The patternsshown in FIGS. 7A and 8A show that video data that has been processedwith the 2:3 pull-down process is formed with four patterns P1, P2, P3,and P4.

[0072] The pattern P1 is a pattern formed with two fields of one normaltop field and one normal bottom field. The pattern P2 is a patternformed with three fields of a normal top field, a normal bottom field,and a top field determined as a repeat field. The pattern P3 is apattern formed with two fields of a normal bottom field and a normal topfield. The pattern P4 is a pattern formed with three fields of a normalbottom field, a normal top field, and a bottom field determined as arepeat field.

[0073] In the examples shown in FIGS. 7A and 8A, since the four patternsP1 to P4 are regularly and continuously detected, it is determined thatthe patterns of the repeat fields of the input video data VIN arecontinuous.

[0074]FIG. 7B shows an example of which patterns of repeat fields arediscontinuous. The patterns shown in FIG. 7B are different from thoseshown in FIG. 7A in that the top field “E” is a repeat field. Preciselyspeaking, although the top field “E” should have been detected as anormal field originally, the top field “E” had been incorrectly detectedas a repeat field in the repeat field detecting process.

[0075] When the top field “E” is determined as a repeat field, thepattern P4 cannot be formed with three fields “d”, “E”, and “e” that arepreceded by the pattern P3. Thus, a new pattern P3′ is formed with twofields “d” and “E”.

[0076] In other words, at a point of which period T1 changes to periodT2 shown in FIG. 7B, the pattern P3 changes to the pattern P3′. Thus, itis determined that the patterns of the repeat fields of the input videodata VIN are discontinuous.

[0077]FIG. 8B shows another example of which patterns of repeat fieldsare discontinuous. In FIG. 8A, a top field “H” is a repeat field. On theother hand, in FIG. 8B, the top field “H” is a normal field. Accuratelyspeaking, although the top field “H” should have been detected as arepeat field originally, the top field “H” had been incorrectly detectedas a normal field in the repeat field detecting process.

[0078] When the top field “H” is determined as a normal field, since thepattern P2 cannot be formed with three fields “G”, “g”, and “H” that arepreceded by the pattern PI formed with fields “F” and “f”, a new patternP1′ is formed with two fields “G” and “g”.

[0079] In other words, at a point of which period T1 changes to periodT2, since the pattern P1 changes to the pattern P1′, it is determinedthat the patterns of the repeat fields of the input video data VIN arediscontinuous.

[0080]FIGS. 7B and 8B show just examples of which patterns of repeatfields are discontinuous. In other words, patterns of repeat fields arediscontinuous in various manners as well as the examples shown in FIGS.7B and 8B.

[0081]FIG. 9 is a schematic diagram showing a transition of statescorresponding to the six patterns (P1, P2, P3, P4, P1′, and P3′)described with reference to FIGS. 7 and 8. In FIG. 9, state F1corresponds to the pattern P1. State F2 corresponds to the pattern P2.State F3 corresponds to the pattern P2. State F3 corresponds to thepattern P3. State F4 corresponds to the pattern P1. State F3′corresponds to the pattern P3′. State F1′ corresponds to the patternP1′.

[0082] As described in FIGS. 7A and 8A, when repeat fields of inputvideo data are regularly and continuously detected, the patterns P1 toP4 are continuously assigned. In other words, when repetitive patternsof input video data are continuous, a main loop of state F1→stateF2→state F3→state F4→state F1 is repeated.

[0083] On the other hand, as described with reference to FIGS. 7B and8B, when repeat fields of input video data are not regularly andcontinuously detected, the patterns P1′ or P3′ are assigned instead ofpatterns P2 or P4. In other words, when repetitive patterns of inputvideo data are discontinuous, state F1′ is assigned after state F1 orF4, and state F3 is assigned after state F3 or F2.

[0084] Next, with reference to FIG. 10, the pattern analyzing processperformed by the pattern analyzing portion 110 in the case that thedetected results of the repeat fields shown in FIG. 7B will bedescribed.

[0085] At step S1, the pattern analyzing portion 110 determines a frameformed with the top field “A” and the bottom field “a” as the patternP1. In the transition loop shown in FIG. 9, when the transition state atstep S1 is state F1, the repeat field is continuous. Thus, at step S2,the pattern analyzing portion 110 sets the continuity flag to “1”.

[0086] At step S3, the pattern analyzing portion 110 determines whetheror not the pattern P2 should be assigned after the pattern P1. Inreality, the pattern analyzing portion 110 determines whether or not thepattern P2 can be formed with the three fields “B”, “b”, and “C”preceded by the fields “A” and “a” determined as the pattern P1. Inother words, when the top field “B” is a normal field, the bottom field“b” is a normal field, and the top field “C” is a repeat field, thepattern P2 can be formed with the three fields. In this case, thepattern analyzing portion 110 determines that state F1 changes to stateF2. Thus, the flow advances to step S4.

[0087] When the top field “B” is a repeat field, the bottom field “b” isa repeat field, or the top field “C” is a normal field, the patternanalyzing portion 110 determines that state F1 changes to state F1′.Thus, the flow advances to step S13.

[0088] At step S4, a flame formed with the three fields “B”, “b”, and“C” is determined as the pattern P2. In the transition loop shown inFIG. 9, when the transition state at step S4 is state F2, the repeatfield is continuous. Thus, at step S5, the pattern analyzing portion 110sets the continuity flag to “1”.

[0089] At step S6, the pattern analyzing portion 110 determines whetheror not the pattern P3 should be assigned after the pattern P2. Inreality, the pattern analyzing portion 110 determines whether or not thepattern P2 can be formed with the two fields “D” and ic “preceded by thefields “B”, “b”, and “C” determined as the pattern P2. In other words,when the top field “D” is a normal field and the bottom field “c” is anormal field, the pattern P3 can be formed with the two fields. In thiscase, the pattern analyzing portion 110 determines that state F2 changesto state F3. Thus, the flow advances to step S7.

[0090] When the top field “D” is a repeat field or the bottom field “c”is a repeat field, the pattern analyzing portion 110 determines thatstate F2 changes to state F3′. Thus, the flow advances to step S15.

[0091] At step S7, a frame formed with the two fields “D” and “c” isdetermined as the pattern P3. In the transition loop shown in FIG. 9,when the transition state at step S7 is state F3, since the repeat fieldis continuous, the flow advances to step S8. At step S8, the patternanalyzing portion 110 sets the continuity flag to “1”.

[0092] At step S9, the pattern analyzing portion 110 determines whetheror not the pattern P4 should be assigned after the pattern P3. Inreality, the pattern analyzing portion 110 determines whether or not thepattern P4 can be formed with the three fields “d”, “E”, and “e”preceded by the fields “c” and “D” determined as the pattern P3. Inother words, when the bottom field “d” is a normal field, the top field“E” is a repeat field, and the bottom field “e” is a repeat field, thepattern P4 can be formed with the three fields. In this case, thepattern analyzing portion 110 determines that state F3 changes to stateF4. Thus, the flow advances to step S10.

[0093] When the bottom field “d” is a repeat field, the top field “E” isa repeat field, or the bottom field “e” is a normal field, the patternanalyzing portion 110 determines that state F changes to state F3′.Thus, the flow advances to step S15. For example, in the determinedresult shown in FIG. 7B, since the top field “E” is determined as arepeat field, the pattern P4 cannot be formed with the three fields “d”,“E”, and “e”. Thus, the flow advances to step S15.

[0094] At step S15, a frame formed with the two fields “d” and “E” isdetermined as the pattern P3′. In the transition loop shown in FIG. 9,when the transition state at step S15 is state F3′, the repeat field isdiscontinuous. Thus, the flow advances to step S16. At step S16, thepattern analyzing portion 110 sets the continuity flag to “0”.Thereafter, the flow returns to step S9.

[0095] At step S9, it is determined whether or not the pattern P4 can beformed with the three fields “e”, “F”, and “f” preceded by the patternP3′. In the example shown in FIG. 7B, since the pattern P4 cannot beformed with the three fields “e”, “F”, and “f”, the flow advances tostep S15.

[0096] In other words, until the pattern P4 is generated in the inputvideo data, a loop of steps S15, S16, and S19 is repeated. In theexample shown in FIG. 7B, since the pattern P4 can be formed with thefields “i”, “J”, and “k”, until the pattern P4 formed with the fields“i”, “J”, and “k” is generated, the loop is repeated. In the loop of thesteps S15, S16, and S9 (namely, in period T2), the generated pattern isP3′ and the continuity flag is “0”.

[0097] At step S10, a frame formed with the three fields “i”, “J”, and“k” is determined as the pattern P4. In the transition loop shown inFIG. 9, when the transition state at step S10 is state F4, since therepeat field is continuous, the flow advances to step S11. At step S11,the pattern analyzing portion 110 sets the continuity flag to “1”.

[0098] At step S12, the pattern analyzing portion 110 determines whetheror not the pattern P1 should be assigned after the pattern P4. Inreality, the pattern analyzing portion 110 determines whether or not thepattern P1 can be formed with two fields “K” and “k” preceded by thefields “i”, “J”, and “k” determined as the pattern P4. In other words,when the top field “K” is a normal field and the bottom field “k” is anormal field, the pattern P1 can be formed with the two fields. In thiscase, the pattern analyzing portion 110 determines that state F4 changesto the step F1. Thus, the flow returns to step S1.

[0099] When the top field “K” is a repeat field or the bottom field “k”is a repeat field, the pattern analyzing portion 110 determines thatstate F4 changes to state F3′. Thus, the flow advances to step S13.

[0100] In other words, as described above, in the example shown in FIG.7B, the pattern analyzing portion 110 outputs the continuity flag=“1”that represents that a repeat field is continuous in period T1 of thepattern P1 to the pattern P4. The pattern analyzing portion 110 outputsthe continuity flag=“0” that represents that a repeat field isdiscontinuous in period T2 of the pattern P3′. The pattern analyzingportion 110 outputs the continuity flag=“1” that represents that arepeat field is continuous in period T2 of the pattern P1 to the patternP4.

[0101] Next, with reference to FIG. 10, the pattern analyzing processperformed by the pattern analyzing portion 110 in the case that thedetected results of the repeat fields shown in FIG. 8B are obtained willbe described.

[0102] The pattern analyzing portion 110 performs the main loop processof step S1 to step S12 for the top field “A” to the bottom field “e”.When the pattern analyzing portion 110 performs the process for the topfield “F” and the bottom field “f”, the flow returns to step S1. Theprocess of the pattern analyzing portion 110 performed for the top field“A” to the bottom field “e” is the same as that shown in FIG. 7B. Thus,for simplicity, only the process of the pattern analyzing portion 110for the top field “F” and the bottom field “f” will be described.

[0103] At step S1, the pattern analyzing portion 110 determines a frameformed with the top field “F” and the bottom field “f” as the patternP1. Tn the transition loop shown in FIG. 9, when the transition state atstep S1 is state F1, since the repeat field is continuous, the flowadvances to step S2. At step S2, the pattern analyzing portion 110 setsthe continuity flag to “1”.

[0104] At step S3, the pattern analyzing portion 110 determines whetheror not the pattern P2 should be assigned after the pattern P1. Inreality, the pattern analyzing portion 110 determines whether or not thepattern P2 can be formed with the three fields “G”, “h”, and “H”preceded by the fields “F” and “f” determined as the pattern P1. Inother words, when the top field “G” is a normal field, the bottom field“g” is a normal field, and the top field “H” is a repeat field, thepattern P2 can be formed with the three fields. In this case, thepattern analyzing portion 110 determines that state F1 changes to stateF2. Thus, the flow advances to step S4.

[0105] When the top field “G” is a repeat field, the bottom field “g” isa repeat field, or the top field “H” is a normal field, the patternanalyzing portion 110 determines that state F1 changes to state F1′.Thus, the flow advances to step S13. For example, in the example of thedetermined results of the repetitive pattern determining process shownin FIG. 8B, since the top field “H” is determined as a normal field, thepattern P4 cannot be formed with the three fields “G”, “g”, and “H”.Thus, the flow advances to step S13.

[0106] At step S13, a frame formed with the two fields “G” and “g” isdetermined as the pattern P1′. In the transition loop shown in FIG. 9,when the transition state at step S13 is state F1′, since the repeatfield is discontinuous, the flow advances to step S14. At step S14, thepattern analyzing portion 110 sets the continuity flag to “0”.Thereafter, the flow returns to step S4.

[0107] At step S4, it is determined whether or not the pattern P2 can beformed with the three fields “H”, “h”, and “I” preceded by the patternP1′. In the example shown in FIG. 8B, since the pattern P4 cannot beformed with the three fields “H”, “h”, and “I”, the flow advances tostep S13.

[0108] In other words, until the pattern P2 is generated in the inputvideo data, the loop of step S13, step S14, and step S3 is repeated. Inthe example shown in FIG. 8B, since the pattern P4 can be formed withthe three fields “L”. “1”, and “M”, until the pattern P4 formed with thefields “L”, “1”, and “M” is generated, the loop is repeated. In the loopof step S13, step S14, and step S3 (namely, in period T2), the patternP1′ is generated and the continuity flag is “0”.

[0109] As is clear from the above description, as with the example shownin FIG. 7B, in the example shown in FIG. 8B, the pattern analyzingportion 110 outputs the continuity flag=“1” that represents that thepattern of the repeat field is continuous in period T1 during which thepattern P1 to the pattern P4 are repeated at a regular order. Thepattern analyzing portion 110 outputs the continuity flag “0” thatrepresents that a repetitive flag is discontinuous in period T2 duringwhich the pattern P3′ is repeated. The pattern analyzing portion 110outputs the continuity flag=“1” that represents that the pattern of therepeat field is continuous in period T3 during which the pattern P1 tothe pattern P4 are repeated at the regular order.

[0110] When the occurrence sequence of repeat fields contained in inputvideo data VIN is continuous, the pattern analyzing portion 110 suppliesthe continuity flag=“1” to the inverse pull-down controlling portion114. When the occurrence sequence of repeat fields contained in inputvideo data VIN is discontinuous, the pattern analyzing portion 110supplies the continuity flag=“0” to the pull-down controlling portion114.

[0111] In addition, the pattern analyzing portion 110 searches 120 flags(that represent whether or not each field is a repetitive file) bufferedin the FIFO register 112, counts the number of flags “1” that representrepeat fields, and supplies the count value C to the inverse pull-downcontrolling portion 114. Since the 120 flags represent up to 24 repeatfields, the count value C ranges from 0 to 24.

[0112] The inverse pull-down controlling portion 114 controls theaddress managing portions 100 and 122, the threshold registers 116 and118, and the video encoding portion 20corresponding to the continuityflags received from the pattern analyzing portion 110 so as to performthe inverse 2:3 pull-down process.

[0113] When a continuity flag received from the pattern analyzingportion 110 is “1”, the inverse pull-down controlling portion 114performs the inverse 2:3 pull-down process for removing a fielddetermined as a repeat field by the comparator 108. When a continuityflag received from the pattern analyzing portion 110 is “0”, the inversepull-down controlling portion 114 does not perform the inverse 2:3pull-down process so as to not remove a field determined as a repeatfield by the comparator 108.

[0114] With reference to FIG. 7B, a real example of the inverse 2:3pull-down process will be described. In period T1 of which a continuityflag received from the pattern analyzing portion 110 is “1”, the inverse2:3 pull-down controlling portion 114 outputs read addresses for thefields “A”, “B”, “D”, “a”, a “b”, and “c” to the address managingportion 122 so as to read the fields “A”, “B”, “D”, “a”, “b”, and “c”other than the field “C” determined as a repeat field by the comparator108 in the fields “A” to “D” and “a” to “c” that are input from theaddress managing portion 100. In other words, the normal 2:3 pull-downprocess for removing all fields determined as repeat fields isperformed.

[0115] On the other hand, in period T2 of which a continuity flagreceived from the pattern analyzing portion 110 is “0”, the inversepull-down controlling portion 114 controls the address managing portion122 so as not to remove fields determined as repeat fields by thecomparator 108. In reality, the inverse pull-down controlling portion114 outputs read addresses for all the fields “E” to “I” and “d” to “h”received from the address managing portion 100 to the address managingportion 122 so as to read all the fields from the memory 102 in such amanner that the fields “E”, “d”, and “H” determined as repeat fields arenot removed.

[0116] In other words, only when the sequence of the repeat fieldscontained in the input video data VIN is regular and the patterns ofrepeat fields are continuous, the inverse pull-down controlling portion114 controls various circuits to perform the inverse 2:3 pull-downprocess. On the other hand, when the sequence of the repeat fieldscontained in the input video data VIN is irregular and the patterns ofrepeat fields are discontinuous, the inverse pull-down controllingportion 114 controls various circuits not to perform the inverse 2:3pull-down process.

[0117] Since the inverse pull-down process is performed as describedabove, even if the normal field “E” (not a repeat field) is incorrectlydetermined as a repeat field, the field “E” is not removed from theinput video data by the 2:3 pull-down process.

[0118] When the inverse 2:3 pull-down process is performed for a videoprogram of which normal video data of 30 Hz has been placed in videodata that has been processed with the 2:3 pull-down process, only repeatfields contained in video data that has been processed with the 2:3pull-down process are removed, and it is prevented that normal fields ofvideo data of 30 Hz are incorrectly removed.

[0119] In addition, the inverse pull-down controlling portion 114performs a process for updating the threshold value T used in theformulas (1) and (2) corresponding to the following formula (3).

T=k×1/C   (3)

[0120] where T is the threshold value used in the formulas (1) and (2);C is the count value received from the pattern analyzing portion 110;and k is a coefficient.

[0121] Next, the reason why the threshold value T used in the formulas(1) and (2) is updated corresponding to the formula (3) will bedescribed.

[0122] As is clear from the formula (3), as the count value C receivedfrom the pattern analyzing portion 110 increases, the threshold value Tdecreases. Thus, as the count value C decreases, the threshold value Tincreases. When the threshold value T becomes small (close to 0), thedetecting conditions for repeat fields expressed by the formulas (1) and(2) become loose. When the threshold value T becomes large, thedetecting conditions for repeat fields expressed by the formulas (1) and(2) become strict.

[0123] As the detecting conditions for repeat fields become loose,repeat fields can be easily detected. However, in this case, theprobability of which a normal field is incorrectly determined as arepeat field becomes high. On the other hand, as the detectingconditions for repeat fields become strict, normal fields can be easilydetected. However, the probability of which a repeat field isincorrectly detected as a normal field becomes high.

[0124] In other words, as the count value C becomes large, the detectingconditions for repeat fields become loose. As the count value C becomeslarge, the detecting conditions for repeat fields become strict. Inother words, while video data processed with the 2:3 pull-down processis being supplied as input video data VIN to the inverse pull-downprocessing portion 10, since the count value C becomes large, thedetecting conditions for repeat fields are relatively loose. Whilenormal video data that has not been processed with the 2:3 pull-downprocess is being supplied as input video data VIN to the inversepull-down processing portion 10, since the count value C becomes small,the detecting conditions for repeat fields become strict. In otherwords, the detecting conditions for repeat fields against video datathat has been processed with the 2:3 pull-down process are more strictthan those against normal video data of 30 Hz.

[0125] In addition, the inverse pull-down controlling portion 114generates control signals that are a prediction mode control signal, aDCT mode control signal, and a scan mode control signal corresponding toa continuity flag received from the pattern analyzing portion 110. Thecontrol signals “Scnt” are supplied to the video encoding portion 20.The control signals “Scnt” are used to select a prediction mode, a DCTmode, and a scan mode of the encoding process of the video encodingportion 20.

[0126] When a continuity flag supplied from the pattern analyzingportion 110 to the inverse pull-down controlling portion 114 is “0”, itmeans that the input video data VIN does not contain a repeat field orthat patterns of repeat fields of the input video data arediscontinuous. Thus, when the continuity flag received from the patternanalyzing portion 110 is “0”, the inverse pull-down controlling portion114 controls the video encoding portion 20 to perform an encodingprocess with a prediction mode determined by the normal predictiondetermining process. In this case, the inverse pull-down controllingportion 114 supplies a prediction mode control signal=“0” to the videoencoding portion 20.

[0127] When a continuity flag supplied from the pattern analyzingportion 110 to the inverse pull-down controlling portion 114 is “1”, itmeans that patterns of repeat fields of input video data are continuous(in other words, the input video data has been processed with the 2:3pull-down process). Thus, when a continuity flag received from thepattern analyzing portion 110 is “1”, the inverse pull-down controllingportion 114 controls the video encoding portion 20 to perform anencoding process in a frame prediction mode. In this case, the inversepull-down controlling portion 114 supplies a prediction mode controlsignal=“1” to the video encoding portion 20.

[0128] Likewise, when a continuity flag received from the patternanalyzing portion 110 is “0”, the inverse pull-down controlling portion114 controls the video encoding portion 20 to perform an encodingprocess in a DCT mode determined with a normal DCT mode determiningprocess. In this case, the inverse pull-down controlling portion 114supplies a DCT mode control signal=“0” to the video encoding portion 20.

[0129] When the continuity flag received from the pattern analyzingportion 110 is “1”, the inverse pull-down controlling portion 114controls the video encoding portion 20 to perform an encoding process ina frame DCT mode. In this case, the inverse pull-down controllingportion 114 supplies a DCT mode control signal=“1” to the video encodingportion 20.

[0130] Likewise, when a continuity flag received from the patternanalyzing portion 110 is “0”, the inverse pull-down controlling portion114 controls the video encoding portion 20to scan DCT coefficients in analternate scan mode. In this case, the inverse pull-down controllingportion 114 supplies a scan mode control signal=“0” to the videoencoding portion 20.

[0131] When a continuity flag received from the patten analyzing portion110 is “1”, the inverse pull-down controlling portion 114 controls thevideo encoding portion 20to scan DCT coefficients in a zigzag scan mode.In this case, the inverse pull-down controlling portion 114 supplies ascan mode control signal=“1” to the video encoding portion 20.

[0132] Next, the reason why the video encoding portion 20 controls theprediction mode, the DCT mode, and the scan mode corresponding to acontinuity flag received from the pattern analyzing portion 110 will bedescribed.

[0133] When a continuity flag is “1”, it means that input video data VINis video data of which a film material has been processed with the 2:3pull-down process. Video data generated from a optical film material bya unit such as a telecine unit is progressive scanned video data. Thisis because when two fields is formed with one frame of an optical filmmaterial, image data of the two fields is the same on time axis.

[0134] Thus, when video data that has been processed with the 2:3pull-down process is encoded, the video encoding portion 20 iscontrolled to perform the encoding process by using frame predictionmode and a frame DCT mode rather than by using one of prediction modeswhichever smaller prediction error and one of DCT modes whicheversmaller generated bits amount so as to generate decoded video datahaving a natural image.

[0135] When the progressive scanned video data processed with the 2:3pull-down process is encoded, DCT coefficients are scanned in the zigzagscan mode so as to effectively obtain signal components of progressivescanned video data.

[0136] When a continuity flag is “0”, input video data VIN isinterlace-scanned video data shot by a video camera. A top field of aframe of interlace-scanned video data is shifted in time from a bottomfield thereof by {fraction (1/60)} second period.

[0137] Thus, when such interlace-scanned video data is encoded, thevideo encoding portion 20 is controlled to perform an encoding processin one of prediction modes whichever smaller prediction error and one ofDCT modes whichever smaller generated bits amount rather than in apredetermined prediction mode and a predetermined DCT mode so as toeffectively, perform the encoding process.

[0138] When interlace-scanned video data is encoded, DCT coefficientsare scanned in the alternate scan mode so as to effectively obtainsignal components of interlace-scanned video data.

[0139] The threshold register 116 is a circuit that buffers thethreshold value T generated by the inverse pull-down controlling portion114. The buffered threshold value T is supplied to the switch 120. Thethreshold register 116 is a register that is used in a digitalbroadcasting system of which the inverse pull-down processing portion 10and the video encoder 20 transmit an encoded video stream on real timebasis.

[0140] The threshold value register 118 is a circuit that buffers athreshold value T′ generated by the inverse pull-down controllingportion 114. The buffered threshold value T′ is supplied to the switch120. The threshold value register 116 is a register that is used in astorage system of which the inverse pull-down processing portion 10 andthe video encoder 20 record an encoded stream to a storage medium.

[0141] The switch circuit 120 is a circuit that switches a circuitcorresponding to a control signal received from the inverse pull-downcontrolling portion 114 and an external control signal. For example,when the inverse pull-down processing portion 10 is applied to a digitalbroadcasting system that transmits an encoded video stream on real timebasis, the switch circuit 120 is connected to a terminal a. When theinverse pull-down processing portion 10 is applied to a storage systemthat records an encoded stream to a storage medium, the switch circuit120 is connected to a terminal b.

[0142] Next, with reference to FIG. 11, the structure of the videoencoding portion 20 corresponding to the MPEG standard and an encodingprocess thereof will be described.

[0143] In the MPEG standard, there are three encoded picture types I, P,and B. In an I picture (Intra-coded picture), when a picture signal isencoded, information of only one picture is used. Thus, when an encodedpicture signal is decoded, information of only the I picture is used. Ina P picture (Predictive-coded picture), as a predictive picture (areference picture for obtaining a difference with the current Ppicture), an I picture or another P picture that has been decoded istemporally followed by the current P picture. In a B picture(Bidirectionally predictive-coded picture), as predictive pictures(reference pictures for obtaining a difference with the current Bpicture),

[0144] three types of pictures that are an I picture or a P picture thatis temporally followed by the current B picture, an I picture or a Ppicture that is temporally preceded by the current B picture, and aninterpolated picture formed with these two types of pictures.

[0145] Video data that has been processed with the inverse 2:3 pull-downprocess by the inverse pull-down processing portion 10is input asmacroblocks to a motion vector detecting circuit 210. The motion vectordetecting circuit 210 processes video data of each frame as an Ipicture, a P picture, or a B picture corresponding to a predeterminedsequence. A picture of each frame that is sequentially input isprocessed as an I picture, a P picture, or a B picture corresponding tothe length of each GOP.

[0146] Video data of a frame processed as an I picture is supplied fromthe motion vector detecting circuit 210 to a forward original pictureportion 211 a of a frame memory 211 and then stored. Video data of aframe processed as a B picture is supplied from the motion vectordetecting circuit 210 to an original picture portion 211 b of the framememory 211 and then stored. Video data of a frame processed as a Ppicture is supplied from the motion vector detecting circuit 210 to abackward original picture portion 211 c of the frame memory 211 and thenstored.

[0147] When a picture of a frame processed as a B picture or a P pictureis input at the next timing, video data of the first P picture stored inthe backward original picture portion 211 c is transferred to thefroward original picture portion 211 a. Video data of the next B pictureis stored (overwritten) to the original picture portion 211 b. Videodata of the next P picture is stored (overwritten) to the backwardoriginal picture portion 211 c. These operations are successivelyrepeated.

[0148] A prediction mode processing circuit 212 is a circuit thatconverts macroblocks of a picture that is read from the frame memory 211into a frame structure or a field structure corresponding to aprediction flag received from an encoding controller 200. When aprediction flag received from the encoding controller 200 represents aframe prediction mode, the prediction mode processing circuit 212outputs macroblocks in the frame structure. When a prediction flagreceived from the encoding controller 200 represents a frame predictionmode, the prediction mode processing circuit 212 outputs macroblocks inthe field structure.

[0149] Next, the format of macroblocks in the frame structurecorresponding to the frame prediction mode and the format of macroblocksin the field structure corresponding to the field prediction mode willbe described.

[0150] As shown in FIG. 12A, macroblocks in the frame structure aremacroblocks of which data of top field (odd field) lines and data ofbottom field (even field) lines coexist in each luminance macroblock.Thus, in the frame prediction mode, four luminance macroblocks Y[1] toY[4] received from the motion vector detecting circuit 210 aremacroblocks in the frame structure as shown in FIG. 12A. The predictionmode processing circuit 212 supplies the four luminance macroblocks Y[1]to Y[4] received from the motion vector detecting circuit 210 to acalculating portion 213. In the frame prediction mode, a frame ispredicted with four luminance macroblocks at a time. Four luminanceblocks correspond to one motion vector. A color difference signal issupplied to the calculating portion 213 in such a manner that data oftop field lines and data of bottom field lines coexist.

[0151] On the other hand, as shown in FIG. 12B, in macroblocks of thefield structure, luminance macroblocks Y[1] and Y[2] are formed withonly data of top field lines and luminance macroblocks Y[3] and Y[4] areformed with only data of bottom field lines. Thus, in the fieldprediction mode, four luminance macroblocks Y[1] to Y[4] in the framestructure are converted into macroblocks in the field structure shown inFIG. 12B and output to the calculating portion 213. In the fieldprediction mode, two luminance blocks Y[1] and Y[2] correspond to onemotion vector. The other two luminance blocks Y[3] and Y[4] correspondto another motion vector. As shown in FIG. 12B, in a color differencesignal, the upper half (four lines) of color difference blocks Cb and Cris a color difference signal of top fields corresponding to theluminance blocks Y[1] and Y[2]. The lower half (four lines) of the colordifference blocks Cb and Cr is a color difference signal of bottomfields corresponding to the luminance blocks Y[3] and Y[4].

[0152] Next, a selecting process of the encoding controller 200 for theframe prediction mode or the field prediction mode will be described.

[0153] The motion vector detecting circuit 210 calculates the sum ofabsolute values of prediction errors in the frame prediction mode andthe sum of absolute values of prediction errors in the field predictionmode and outputs the calculated results to the encoding controller 200so as to select the frame prediction mode or the field prediction mode.The prediction errors are motion estimation residuals (ME residuals).

[0154] The control signals Scnt (the prediction mode control signal, theDCT mode control signal, and the scan mode control signal) are suppliedfrom the inverse pull-down processing portion 10 to the encodingcontroller 200. The encoding controller 200 receives the prediction modecontrol signal and the sum of absolute values of prediction errors inthe frame prediction mode and the field prediction mode from the inversepull-down processing portion 10 and controls the prediction mode processof the prediction mode processing circuit 212 corresponding to theprediction mode control signal and the sum of absolute values ofprediction errors in the frame prediction mode and the field predictionmode.

[0155] First of all, the case that the prediction mode control signalsupplied from the inverse pull-down processing portion 10 to theencoding controller 200 is “0” will be described.

[0156] When the prediction mode control signal supplied to the encodingcontroller 200 is “0”, the input video data VIN supplied to the inversepull-down processing portion 10 is video data of which patterns ofrepeat fields are discontinuous or video data that does not containrepeat fields at all. In other words, the input video data VIN is normalinterlaced video data generated by a video camera or the like.

[0157] In this case, the encoding controller 200 performs the normalprediction mode selecting process. In the normal prediction determiningprocess, the sum of absolute values of predictive errors in the frameprediction mode and the sum of absolute values of predictive errors inthe field prediction mode are compared. Corresponding to the comparedresult, a prediction mode with a smaller sum is selected. When the sumof absolute values of predictive errors in the field prediction mode issmaller than that in the frame prediction mode, the encoding controller200 supplies a prediction flag that represents the field prediction modeto the prediction mode processing circuit 212. When the sum of absolutevalues of prediction errors in the frame prediction mode is smaller thanthat in the field prediction mode, the encoding controller 200 suppliesa prediction flag that represents the frame prediction mode to theprediction mode processing circuit 212.

[0158] Next, the case that a prediction mode control signal suppliedfrom the inverse pull-down processing portion 10to the encodingcontroller 200 is “1” will be described.

[0159] When a prediction mode control signal supplied to the encodingcontroller 200 is “1”, input video data VIN supplied to the inversepull-down processing portion 10 is video data containing repeat fieldsthat are continuous and regular. Thus, the input video data VIN can bedetermined as progressive video data which has been processed from afilm material by using the 2:3 pull-down process.

[0160] In this case, the encoding controller 200 supplies a predictionflag corresponding to a frame prediction mode to the prediction modeprocessing circuit 212 so as to perform the frame prediction modeprocess regardless of the compared result of the sum of absolute valuesof prediction errors in the frame prediction mode and the sum ofabsolute values of prediction errors in the field prediction mode. Evenif it is determined that the sum of absolute values of prediction errorsin the field prediction mode is smaller than the sum of absolute valuesof prediction errors in the frame prediction mode, the encodingcontroller 200 controls the prediction mode processing circuit 212 toforcedly perform the frame prediction mode process.

[0161] The reason why the encoding controller 200 controls theprediction mode processing circuit to forcedly perform the frameprediction mode process is as follows. In the case of progressive videodata obtained from a film material, there is no temporal differencebetween a top field and a bottom field. Thus, when the prediction modeprocessing circuit 212 performs the frame prediction mode process,encoded video data of a natural pattern can be generated.

[0162] As described above, since the video encoding portion 20 cancontrol the prediction mode corresponding to the inverse pull-downprocess of the inverse pull-down processing portion 10, the encodingprocess can be properly performed for video data that has been processedwith the inverse 2:3 pull-down process.

[0163] In addition, the motion vector detecting circuit 210 generatesthe sum of absolute values of prediction errors in each prediction modeso as to select intra-picture prediction mode, forward prediction mode,backward prediction mode, or bidirectional prediction mode. In reality,the motion vector detecting circuit 210 obtains the difference betweenthe absolute value of the sum of signals Aij of macroblocks of areference picture and the sum of the absolute value of the signals Aijof the macroblocks (namely, |ΣAij|−Σ|Aij|) as the sum of absolute valuesof prediction errors in the intra-picture prediction mode. In addition,the motion vector detecting circuit 210 obtains the sum of the absolutevalue of the difference between the signals Aij of the macroblocks ofthe reference picture and signals Bij of macroblocks of a predictionpicture (namely, Σ|Aij−Bij|) as the sum of absolute values of predictionerrors in the forward prediction mode. As with the case of the forwardprediction mode, the sum of absolute values of prediction errors in eachof the backward prediction mode and the bidirectional prediction mode isobtained (however, a prediction picture of each of the backwardprediction mode and the bidirectional prediction mode is different fromthe prediction picture in the forward prediction mode).

[0164] The encoding controller 200 receives information of the sum ofabsolute values in each prediction direction and selects the smallestvalue from the sum in each prediction direction as the sum of absolutevalues of prediction errors in the inter-picture prediction mode. Inaddition, the encoding controller 200 compares the sum of absolutevalues of prediction errors in the inter-picture prediction mode and thesum of absolute values of prediction errors in the intra-pictureprediction mode and selects one of these modes with a smaller value. Inother words, when the sum of absolute values of prediction errors in theintra-picture prediction mode is smaller than that in the inter-pictureprediction mode, the intra-picture prediction mode is selected. When thesum of absolute values of prediction errors in the inter-pictureprediction is smaller than that in the intra-picture prediction, aprediction mode with the smallest value corresponding to the forwardprediction mode, the backward prediction mode, or the bidirectionalprediction mode is selected. The encoding controller 200 supplies acontrol signal that represents the selected prediction mode to thecalculating portion 213.

[0165] The calculating portion 213 controls the switch corresponding toa prediction mode control signal received from the encoding controller200 so as to perform a calculation for the intra-picture predictionmode, the forward prediction mode, the backward prediction mode, or thebidirectional prediction mode. In reality, when a prediction modecontrol signal received from the encoding controller 200 represents theintra-picture prediction mode, the calculating portion 213 places theswitch to a terminal a position. When a prediction mode control signalreceived from the encoding controller 200 represents the forwardprediction mode, the calculating portion 213 places the switch to aterminal b position. When a prediction mode control signal received fromthe encoding controller 200 represents the backward prediction mode, thecalculating portion 213 places the switch to a terminal c position. Whena prediction mode control signal received from the encoding controller200 represents the bidirectional prediction mode, the calculatingportion 213 places the switch to a terminal d position.

[0166] The motion vector detecting circuit 210 detects a motion vectorbetween a prediction picture and a reference picture corresponding to aprediction mode selected from the above-described four prediction modesby the encoding controller 200 and outputs the motion vector to avariable length code encoding circuit 218 and a motion compensatingcircuit 224.

[0167] A DCT mode processing circuit 215 is a circuit that converts theformat of macroblocks supplied to a DCT circuit 216 into macroblocks ina frame structure for a frame DCT process or macroblocks in a fieldstructure for a field DCT process corresponding to a DCT mode controlsignal received from the encoded controller 200.

[0168] Macroblocks in the frame structure for the frame DCT mode aremacroblocks of which top field lines and bottom field lines coexist ineach of four luminance macroblocks Y[1], Y[2], Y[3], and Y[4] as shownin FIG. 13A. Macroblocks in the field structure for the field DCT modeare macroblocks of which luminance macroblocks Y[1] and Y[2] of fourluminance macroblocks are formed with only top field lines and luminancemacroblocks Y[3] and Y[4] are formed with only bottom field lines asshown in FIG. 13B.

[0169] Next, a selecting process of the encoding controller 200 for theframe DCT mode or the field DCT mode will be described.

[0170] The DCT mode processing circuit 215 virtually calculates agenerated bit amount in the case that macroblocks in the frame structureis processed in the frame DCT mode and a generated bit amount in thecase that macroblocks in the field structure is processed in the fieldDCT mode so as to select the frame DCT mode or the field DCT mode. TheDCT mode processing circuit 215 supplies the calculated results to theencoding controller 200. Alternatively, in the frame DCT mode, bycalculating the sum of the absolute value of the difference of levels ofadjacent top fields and the absolute value of the difference of levelsof adjacent bottom fields (or the sum of squares), a generated bitsamount can be virtually obtained. In the field DCT mode, by calculatingthe sum of the absolute value of the difference of levels of adjacentlines of a top field and the sum of the absolute value of the differenceof levels of adjacent lines of a bottom field, a generated bits amountcan be virtually obtained.

[0171] The encoding controller 200 receives the DCT mode control signalfrom the inverse pull-down processing portion 10and the generated bitsamount in the frame DCT mode and the generated bits amount in the fieldDCT mode from the DCT mode processing circuit 215 and controls the DCTmode for the DCT mode processing circuit 212 corresponding to the DCTmode control signal, the generated bits amount in the frame DCT mode,and the generated bits amount in the field DCT mode.

[0172] Next, the case that the DCT mode control signal supplied from theinverse pull-down processing portion 10 to the encoding controller 200is “0” will be described.

[0173] When the DCT mode control signal supplied to the encodingcontroller 200 is “0”, input video data VIN supplied to the inversepull-down processing portion 10 is video data containing repeat fieldswhose patterns are discontinuous or video data that does not containrepeat fields. In other words, the input video data VIN can bedetermined as normal interlaced video data generated by a video cameraor the like.

[0174] In this case, the encoding controller 200 performs a normal DCTmode determining process. In the normal DCT mode determining process, agenerated bits amount in the frame DCT mode received from the DCT modeprocessing circuit 215 and a generated bits amount in the field DCT modereceived from the DCT mode processing circuit 215 are compared. A DCTmode with a smaller generated bits amount is selected corresponding tothe compared results. In other words, a DCT mode with higher encodingefficiency is selected. Thus, when the generated bit amount in the fieldDCT mode is smaller than that in the frame DCT mode, since the encodingefficiency in the field DCT mode is higher than that in the frame DCTmode, the encoding controller 200 selects the field DCT mode. When thegenerated bits amount in the frame DCT mode is smaller than that in thefield DCT mode, since the encoding efficiency in the frame DCT mode ishigher than that in the field DCT mode, the encoding controller 200selects the frame DCT mode. The encoding controller 200 supplies a DCTflag corresponding to the selected frame DCT mode to the DCT modeprocessing circuit 215.

[0175] Next, the case that the DCT mode control signal supplied from theinverse pull-down processing portion 10 to the encoding controller 200is “1” will be described.

[0176] When the DCT mode control signal supplied to the encodingcontroller 200 is “1”, input video data VIN supplied to the inversepull-down processing portion 10 is video data containing repeat fieldsthat are continuous and regular. Thus, the input video data VIN can bedetermined as progressive video data that has been generated from a filmmaterial and that has been processed with the 2:3 pull-down process.

[0177] In this case, the encoding controller 200 controls the DCT modeprocessing circuit 215 to perform the frame DCT mode process regardlessof which of the generated bits amount in the frame DCT mode or thegenerated bits amount in the field DCT mode received from the DCT modeprocessing circuit 215 is large so as to perform the frame DCT modeprocess. Even if it is determined that the generated bits amount in thefield DCT mode is smaller than that in the frame DCT mode, the encodingcontroller 200 supplies the DCT flag to the DCT mode processing circuit215 to forcedly perform the frame DCT mode process.

[0178] The reason why the DCT mode processing circuit 215 forcedlyperforms the frame DCT mode process is as follows. In the case ofprogressive video data generated from a film material, there is notemporal difference between a top field and a bottom field. Thus, asshown in FIG. 12A, when the DCT mode processing circuit 215 performs inthe frame DCT mode process, encoded video data of a natural pattern canbe generated.

[0179] As described above, since the video encoding portion 20cancontrol a DCT mode corresponding to the inverse pull-down process of theinverse pull-down processing portion 10, the video encoding portion 20can properly encode video data that has been processed with the inverse2:3 pull-down process.

[0180] In addition, the DCT mode processing circuit 215 outputs a DCTflag that represents a selected DCT mode to the variable length codeencoding circuit 218 and the motion compensating circuit 224.

[0181] The DCT circuit 216 receives video data of an I picture from theDCT mode processing circuit 215, performs the DCT process for the videodata, and generates two-dimensional DCT coefficients. In addition, theDCT circuit 216 scans the two-dimensional DCT coefficients in the ordercorresponding to a selected scan mode.

[0182] When the inverse pull-down processing portion 10 supplies a scanmode control signal=“0” to the encoding controller 200, since inputvideo data VIN is interlace-scanned video data, the encoding controller200 controls the DCT circuit 216 to scan the DCT coefficients in thealternative scan method.

[0183] On the other hand, when the inverse pull-down processing portion10 supplies a scan mode control signal=“1” to the encoding controller200, since input video data VIN is progressive-scanned video data thathas been processed with the 2:3 pull-down process, the encodingcontroller 200 controls the DCT circuit to scan the DCT coefficients inthe zigzag scan mode.

[0184] Since the inverse pull-down processing portion 10 controls thescan mode (the alternate scan mode or the zigzag scan mode), thescanning process can be performed corresponding to the format of asignal to be encoded. Thus, DCT coefficients can be effectivelyobtained.

[0185] The DCT coefficients are output from the DCT circuit 216 to aquantizing circuit 217. The quantizing circuit 217 quantizes the DCTcoefficients with a quantizing scale corresponding to a data storageamount (a buffer storage amount) of a transmission buffer 219 andsupplies the resultant DCT coefficients to the variable length codeencoding circuit 218.

[0186] The variable length code encoding circuit 218 converts video data(in this example, data of an I picture) received from the quantizingcircuit 217 into variable length code such as Huffman code correspondingto the quantizing scale received from the quantizing circuit 217 andoutputs the resultant data to the transmission buffer 219.

[0187] The variable length code encoding circuit 218 performs thevariable length code encoding process for the motion vector detected bythe motion vector detecting circuit 210, the prediction flag thatrepresents the frame prediction mode or the field prediction mode, theprediction mode flag that represents the intra-picture prediction, theforward prediction mode, the backward prediction mode, or thebidirectional prediction mode, the DCT flag that represents the frameDCT mode or the field DCT mode, and the quantizing scale used in thequantizing circuit 217.

[0188] The transmission buffer 219 temporarily stores input data andsupplies data corresponding to the storage amount to the quantizingcircuit 217. When the remaining amount of data of the transmissionbuffer 219 increases to the allowable upper limit, the transmissionbuffer 219 increases the quantizing scale of the quantizing circuit 217corresponding to a quantization control signal so as to decrease thedata amount of the quantized data. In contrast, when the remainingamount of data decreases to the allowable lower limit, the transmissionbuffer 219 decreases the quantizing scale of the quantizing circuit 217corresponding to the quantization control signal so as to increase thedata amount of the quantized data. Thus, the transmission buffer 219 canbe prevented from overflowing or underflowing.

[0189] Data stored in the transmission buffer 219 is read and output tothe transmission portion 30 at a predetermined timing.

[0190] On the other hand, data of an I picture that is output from thequantizing circuit 217 is input to an inversely quantizing circuit 220.The inversely quantizing circuit 220 inversely quantizes the datacorresponding to the quantizing scale received from the quantizingcircuit 217. Output data of the inversely quantizing circuit 220 isinput to an IDCT (Inversely Discrete Cosine Transform) circuit 221. TheIDCT circuit 221 performs an IDCT process for the data received from theinversely quantizing circuit 220 and supplies the resultant data to aforward prediction picture portion 223 a of a frame memory 223 through acalculating unit 222.

[0191] When the motion vector detecting circuit 210 processes video dataof each frame that is sequentially input as I, B, P, B, P, and Bpictures, the motion vector detecting circuit 210 processes video dataof the first frame as an I picture. Before processing video data of thenext frame as a B picture, the motion vector detecting circuit 210processes video data of the third frame as a P picture. Since a Bpicture is backward predicted, unless a P picture as a backwardprediction picture is prepared before the P picture, the B picturecannot be decoded.

[0192] Thus, after processing video data of an I picture, the motionvector detecting circuit 210 processes video data of a P picture storedin the backward original picture portion 211 c. As with theabove-described case, the sum of absolute values of residuals betweenframes for each macroblock (prediction errors) is supplied from themotion vector detecting circuit 210 to the encoding controller 200. Theencoding controller 200 selects the prediction mode (the fieldprediction mode or the frame prediction mode) corresponding to theprediction mode control signal received from the inverse pull-downprocessing portion 10 and the sum of absolute values of predictionerrors of macroblocks of the P picture.

[0193] In addition, the encoding controller 200 sets a prediction mode(the intra-picture prediction mode, the forward prediction mode, thebackward prediction, or the bidirectional prediction mode) of thecalculating portion 213 corresponding to the sum of absolute values ofprediction errors of macroblocks of the P picture. When theintra-picture prediction mode is set, the calculating portion 213 placesa switch 213 d to the contact a position. Thus, as with data of an Ipicture, data of a P picture is supplied to the transmission paththrough the DCT mode processing circuit 215, the DCT circuit 216, thequantizing circuit 217, the variable length code encoding circuit 218,and the transmission buffer 219. The data of a P picture is supplied toa backward prediction picture portion 223 b of the frame memory 223through the inversely quantizing circuit 220, the IDCT circuit 221, andthe calculating unit 222. The supplied data is stored to the backwardprediction picture portion 223 b.

[0194] When the forward prediction mode is set, the calculating portion213 places the switch 213 d to the contact b position. In addition,picture data (an I picture in the case that the P picture is encoded)stored in the forward prediction picture portion 223 a of the framememory 223 is read. The motion compensating circuit 224 compensates themotion of the picture data corresponding to a motion vector that isoutput from the motion vector detecting circuit 210. In other words,when the encoding controller 200 controls the motion compensatingcircuit 224 to perform the forward prediction mode process, the motioncompensating circuit 224 reads data from the forward prediction pictureportion 223 a in such a manner that the read address of the forwardprediction picture portion 223 a is shifted from the position of thecurrent macroblock by the length of the motion vector and generatesprediction video data.

[0195] The prediction video data that is output from the motioncompensating circuit 224 is supplied to a calculating unit 213 a. Thecalculating unit 213 a subtracts prediction video data corresponding toa macroblock received front the motion compensating circuit 65 from dataof a macroblock of a reference picture received from the prediction modeprocessing circuit 212 and outputs the difference (prediction error).The difference data is supplied to the transmission path through the DCTmode processing circuit 215, the DCT circuit 216, the quantizing circuit217, the variable length code encoding circuit 218, and the transmissionbuffer 219. The DCT mode determining process for the DCT mode processingcircuit 215 is performed by the encoding controller 200. As with thecase of data of an I picture, the encoding controller 200 determines aDCT mode corresponding to the DCT mode control signal received from theinverse pull-down processing portion 10, the generated bit amount in theframe DCT mode, the generated bit amount in the field DCT mode.

[0196] Next, the difference data is locally decoded by the inverselyquantizing circuit 20 and the IDCT circuit 221 and input to thecalculating unit 222. The same data as the prediction video datasupplied to the calculating unit 213 a is supplied to the calculatingunit 222. The calculating unit 222 adds the prediction video data thatis output from the motion compensating circuit 224 and the differencedata that is output from the IDCT circuit 221. Thus, video data of theoriginal (decoded) P picture is obtained. The video data of the Ppicture is supplied to the backward prediction picture portion 223 b ofthe frame memory 223 and then stored.

[0197] After data of the I picture and data of the P picture are storedto the forward prediction picture portion 223 a and the backwardprediction picture portion 223 b, the motion vector detecting circuit210 processes a B picture. As with the above-described case, the sum ofabsolute values of the difference values between frames for macroblocksof the B picture (prediction errors) is supplied from the motion vectordetecting circuit 210 to the encoding controller 200. The encodingcontroller 200 selects a prediction mode (the field prediction mode orthe field prediction mode) of the prediction mode processing portion 212corresponding to the prediction mode control signal received from theinverse pull-down processing portion 10 and the sum of absolute valuesof prediction errors of macroblocks of the P picture.

[0198] In addition, the encoding controller 200 sets a prediction mode(the intra-picture prediction mode, the forward prediction mode, thebackward prediction mode, or the bidirectional prediction mode) for thecalculating portion 213 corresponding to the sum of absolute values ofprediction errors of macroblocks of the P picture.

[0199] As described above, in the intra-picture prediction mode or theforward prediction mode, the switch 213 d is placed to the contract aposition or the contact b position, respectively. At this point, thesame process as the case of the P picture is performed and the resultantdata is sent.

[0200] In contrast, in the backward prediction mode or the bidirectionalprediction mode, the switch 213 d is placed to the contract c positionor the contact d position, respectively. In the backward prediction modeof which the switch 213 d is placed to the contact c position, picturedata (I picture or P picture in the case that the B picture is encoded)is read from the backward prediction picture portion 223 b. The motioncompensating circuit 224 compensates the motion corresponding to themotion vector that is output from the motion vector detecting circuit210. In other words, when the encoding controller 200 controls themotion compensating circuit 224 to perform the backward prediction modeprocess, the motion compensating circuit 224 reads data from thebackward prediction picture portion 223 b in such a manner that the readaddress of the backward prediction picture portion 223 b is shifted fromthe position of the current output macroblock by the length of themotion vector and generates prediction video data.

[0201] The prediction video data that is output from the motioncompensating circuit 224 is supplied to the calculating unit 213 b. Thecalculating unit 213 b subtracts prediction video data received from themotion compensating circuit 224 from data of a macroblock of a referencepicture received from the prediction mode processing circuit 212 andoutputs the difference. The difference data is sent to the transmissionpath through the DCT mode processing circuit 215, the DCT circuit 216,the quantizing circuit 217, the variable length code encoding circuit218, and the transmission buffer 219.

[0202] The DCT mode determining process for the DCT mode processingcircuit 215 is performed by the encoding controller 200. As with thecase of an I picture and a P picture, the encoding controller 200determines a DCT mode corresponding to the DCT mode control signalreceived from the inverse pull-down processing portion 10, the generatedbit amount in the frame DCT mode, the generated bit amount in the fieldDCT mode.

[0203] As with the above-described process, in the DCT process performedby the DCT circuit 216, when a scan mode control signal received fromthe inverse pull-down processing portion 10 is “0”, the alternate-scanmode is used. When a scan mode control signal received from the inversepull-down processing portion 10 is “1”, the zigzag scan mode is used.

[0204] In the bidirectional prediction mode of which the switch 213 d isplaced to the contact d position, picture data of an I picture andpicture data of a P picture are read from the forward prediction pictureportion 223 a and the backward prediction picture portion 223 b,respectively. The motion compensating circuit 224 compensates themotions of the picture data corresponding to the motion vector receivedfrom the motion vector detecting circuit 210.

[0205] In other words, when the encoding controller 200 controls themotion compensating circuit 224 to perform the bidirectional predictionmode process, the motion compensating circuit 224 reads data from theforward prediction picture portion 223 a and the backward predictionpicture portion 223 b in such a manner that the read addresses of theforward prediction picture portion 223 a and the backward predictionpicture portion 223 b are shifted from the position of the currentoutput macroblock of the motion vector detecting circuit 210 by thelengths of the motion vectors for the forward prediction picture and thebackward prediction picture.

[0206] The prediction video data that is output from the motioncompensating circuit 224 is supplied to the calculating unit 213 c. Thecalculating unit 213 c subtracts the average value of prediction videodata received from the motion compensating circuit 224 from data of amacroblock of a reference picture received from the motion vectordetecting circuit 210 and outputs the difference. The difference data issent to the transmission path through the DCT mode processing circuit215, the DCT circuit 216, the quantizing circuit 217, the variablelength code encoding circuit 218, and the transmission buffer 219.

[0207] Since a B picture is not used as a prediction picture of anotherpicture, the B picture is not stored in the frame memory 223.

[0208] In the frame memory 223, when necessary, the forward predictionpicture portion 223 a and the backward prediction picture portion 223 bare bank-switched. In other words, for a particular reference picture,data stored in one of the forward prediction picture portion 223 a andthe backward prediction picture portion 223 b is selected and output asa forward prediction picture or a backward prediction picture.

[0209] In the above description, luminance blocks were explained.Likewise, color difference blocks are processed and sent as macroblocksshown in FIGS. 12A to 13B. In a process for a color difference block, amotion vector used in a process for a luminance block is halved in thevertical direction and the horizontal direction is used.

[0210] As described above, a video data processing apparatus accordingto the present invention comprises a repeat field detecting means fordetecting the repeat field contained in the video data, an analyzingmeans for analyzing a pattern of the repeat field contained in the videodata corresponding to the detected results of the repeat field detectingmeans and determining whether the pattern of the repeat field iscontinuous or discontinuous, a video data processing means forperforming an inverse 2 3 pull-down process for removing the repeatfield contained in the video data, and a controlling means forcontrolling the video data processing means to remove a field determinedas a repeat field by the repeat field detecting means from the videodata in a period that the patten of the repeat field is determinedcontinuous by the analyzing means and for controlling the video dataprocessing means not to remove a field determined as a repeat field bythe repeat field detecting means from the video data in a period thatthe pattern of the repeat field is determined discontinuous by theanalyzing means.

[0211] A video data processing apparatus according to the presentinvention comprises a repeat field detecting means for detecting therepeat field contained in the video data, an analyzing means fordetermining whether or not an occurrence sequence of the repeat fieldcontained in the video data is regular corresponding to the detectedresults of the repeat field detecting means, a video data processingmeans for performing an inverse 2:3 pull-down process for removing therepeat field contained in the video data, and a controlling means forcontrolling the video data processing means to remove a field determinedas a repeat field by the repeat field detecting means from the videodata in a period that the occurrence sequence of the repeat field isdetermined regular by the analyzing means and for controlling the videodata processing means not to remove a field determined as a repeat fieldby the repeat field detecting means from the video data in a period thatthe occurrence sequence of the repeat field is determined irregular bythe analyzing means.

[0212] In other words, in the video data processing apparatus accordingto the present invention, since the inverse 2:3 pull-down process iscontrolled corresponding to the continuity of a pattern of a repeatfield or the regularity of an occurrence sequence of repeat fields, whena pattern of a repeat field is continuous, the repeat field isaccurately removed. When a pattern of a repeat field is discontinuous, afield incorrectly determined as a repeat field can be prevented frombeing removed. Thus, in the video data processing apparatus according tothe present invention, even if input video data that has been processedwith the 2:3 pull-down process contains large noise or video data thathas been processed with the 2:3 pull-down process contains video data of30 Hz, a field that is not a repeat field can be prevented fromincorrectly removed.

[0213] A video data processing apparatus according to the presentinvention comprises an analyzing means for analyzing the continuity of arepeat field contained in the video data and determining whether thecurrent field of the video data is a field of the progressive-scannedvideo material or a field of the interlace-scanned video material, avideo data processing means for removing the repeat field from the videodata, and a controlling means for controlling the video data processingmeans to remove a repeat field contained in the progressive-scannedvideo material and not to remove a field contained in theinterlace-scanned video material corresponding to the analyzed resultsof the repeat field analyzing means.

[0214] In the video data processing apparatus according to the presentinvention, corresponding to the continuity of a pattern of a repeatfield contained in input video data, it is determined whether anoriginal material is a progressive material that has been processed withthe 2:3 pull-down process or an interlace material that has a frequencyof a normal television signal. Corresponding to the determined result,the inverse 2:3 pull-down process is performed for the progressivematerial. The inverse 2:3 pull-down process is not performed for theinterlace material. Thus, even if progressive-scanned video data thathas been processed with the 2:3 pull-down process containsinterlace-scanned video data of 30 Hz, a field that is not a repeatfield can be prevented from being incorrectly removed.

[0215] A video data encoding apparatus according to the presentinvention comprises an analyzing means for analyzing a pattern of therepeat field contained in the video data and determining whether or notthe pattern of the repeat field is continuous, a video data processingmeans for removing the repeat field from the video data, an encodingmeans for encoding video data that is output from the video dataprocessing means, and a controlling means for controlling the video dataprocessing means to remove a field determined as a repeat field by therepeat field detecting means and perform an encoding process in a frameprediction mode and a frame DCT mode in a period that the pattern of therepeat field is determined continuous by the analyzing means and forcontrolling the video processing means not to remove a field determinedas a repeat field by the repeat field detecting means and perform anencoding process in one of a frame prediction mode and a fieldprediction mode and one of a frame DCT mode and a field DCT mode in aperiod that the pattern of the repeat field is determined discontinuousby the analyzing means.

[0216] In the video data encoding apparatus according to the presentinvention, since an encoding mode of the encoding means s controlledcorresponding to the continuity of a pattern of a repeat field. Thus,the encoding process can be performed in an encoding mode correspondingto video data that has been processed with the 2:3 pull-down process. Inaddition, the encoding process can be performed in an encoding modecorresponding to normal video data of 30 Hz. In the video data encodingapparatus according to the present invention, the video data processingmeans that performs the inverse 2:3 pull-down process is controlledcorresponding to the continuity of a pattern of a repeat field. Since arepeat field is securely removed from video data that has been processedwith the 2:3 pull-down process, the encoding efficiency can be improved.In addition, a field that is not a repeat field can be incorrectlyremoved from normal video data of 30 Hz.

[0217] A video data encoding apparatus according to the preset inventioncomprises an analyzing means for analyzing a repetitive pattern of therepeat field contained in the video data and determining whether thecurrent field of the video data is a field of the first video materialor a field of the second video material, a video data processing meansfor removing the repeat field from the video data, an encoding means forencoding video data that is output from the video data processing means,and a controlling means for controlling an operation of the video dataprocessing means and an encoding mode of the encoding meanscorresponding to the analyzed results of the analyzing means.

[0218] A video data encoding apparatus according to the presentinvention comprises an analyzing means for analyzing the continuity of arepeat field contained in the video data and determining whether thevideo data is the progressive-scanned video data or theinterlace-scanned video data, a video data processing means for removingthe repeat field from the video data, an encoding means for encodingvideo data that is output from the video data processing means, and acontrolling means for controlling the video data processing means toremove a repeat field contained in the progressive-scanned videomaterial and not to remove a field contained in the interlace-scannedvideo material corresponding to the analyzed results of the analyzingmeans and for controlling the encoding means to select an encoding modecorresponding to the progressive-scanned video material or theinterlace-scanned video material.

[0219] In other words, in the encoding apparatus according to thepresent invention, the continuity of a repeat field is analyzed. It isdetermined whether an original material of input video data is aprogressive-scanned video material or an interlace-scanned videomaterial corresponding to the analyzed result. The encoding means iscontrolled to select an encoding mode for a progressive-scanned videomaterial or an interlaced video material corresponding to the determinedresult. Thus, the prediction encoding mode, DCT mode, or scan modecorresponding to an original material of input video data can beselected. Thus, the picture quality of encoded video data can beimproved.

[0220] Moreover, in the video data encoding apparatus according to thepresent invention, a repeat field is removed from a progressive materialthat has been processed with the 2:3 pull-down process. Thus, since theredundancy of video data that is encoded can be reduced, thecompression-encoding process can be performed with high compressionefficiency. In addition, even if a repeat field is detected from aninterlaced material, the repeat field is not removed. Consequently, thedeterioration of picture quality due to an incorrectly detected repeatfield can be securely prevented.

1. A video data processing apparatus for removing a repeat field fromvideo data, comprising: repeat field detecting means for detecting therepeat field contained in the video data; analyzing means for analyzinga pattern of the repeat field contained in the video data correspondingto the detected results of said repeat field detecting means anddetermining whether the pattern of the repeat field is continuous ordiscontinuous; video data processing means for removing the repeat fieldcontained in the video data; and controlling means for controlling saidvideo data processing means to remove a field determined as a repeatfield by said repeat field detecting means from the video data in aperiod that the patten of the repeat field is determined continuous bysaid analyzing means and for controlling said video data processingmeans not to remove a field determined as a repeat field by said repeatfield detecting means from the video data in a period that the patternof the repeat field is determined discontinuous by said analyzing means.2. The video data processing apparatus as set forth in claim 1, whereinsaid analyzing means determines that the pattern of the repeat field iscontinuous in a period of which predetermined patterns formed with aplurality of fields are regularly repeated, and wherein said analyzingmeans determines that the pattern of the repeat field is discontinuousin a period of which predetermined patterns formed with a plurality offields are not regularly repeated.
 3. The video data processingapparatus as set forth in claim 1, further comprising: encoding meansfor encoding video data that is output from said video data processingmeans, wherein said controlling means controls an encoding mode of saidencoding means depending on whether the pattern is continuous ordiscontinuous.
 4. The video data processing apparatus as set forth inclaim 3, wherein said controlling means controls said encoding means toperform a prediction encoding process in a frame prediction mode in aperiod that the pattern is determined continuous, and wherein saidcontrolling means controls said encoding means to perform a predictionencoding process in one of a frame prediction mode and a fieldprediction mode in a period that the pattern is determineddiscontinuous.
 5. The video data processing apparatus as set forth inclaim 3, wherein said controlling means controls said encoding means toperform a prediction encoding process in a frame prediction mode in aperiod that the pattern is determined continuous, and wherein saidcontrolling means controls said encoding means to perform a predictionencoding process in one of a frame prediction mode and a fieldprediction mode whichever a smaller generated bit amount in a periodthat the pattern is determined discontinuous.
 6. The video dataprocessing apparatus as set forth in claim 3, wherein said controllingmeans controls said encoding means to perform a DCT process in a frameDCT mode in a period that the pattern is determined continuous, andwherein said controlling means controls said encoding means to perform aDCT process in one of a frame DCT mode and a field DCT mode in a periodthat the pattern is determined discontinuous.
 7. The video dataprocessing apparatus as set forth in claim 3, wherein said controllingmeans controls said encoding means to perform a DCT process in a frameDCT mode in a period that the pattern is determined continuous, andwherein said controlling means controls said encoding means to perform aDCT process in one of a frame DCT mode and a field DCT mode whichever asmaller motion compensation residual in a period that the pattern isdetermined discontinuous.
 8. The video data processing apparatus as setforth in claim 3, wherein said controlling means controls said encodingmeans to scan DCT coefficients in a zigzag scan mode in a period thatthe pattern is determined continuous, and wherein said controlling meanscontrols said encoding means to scan DCT coefficients in an alternatescan mode in a period that the pattern is determined discontinuous. 9.The video data processing apparatus as set forth in claim 3, whereinsaid controlling means controls said encoding means to perform aprediction encoding process in a frame prediction mode, a DCT process ina frame DCT mode, and scan DCT coefficients in a zigzag scan mode in aperiod that the pattern is determined continuous, and wherein saidcontrolling means controls said encoding means to perform a predictionencoding process in one of a frame prediction mode and a fieldprediction mode whichever a smaller generated bit amount, perform a DCTprocess in one of a frame DCT mode and a field DCT mode whichever asmaller motion compensation residual, and scan DCT coefficients in analternate scan mode in a period that the pattern is determineddiscontinuous.
 10. The video data processing apparatus as set forth inclaim 1, wherein said controlling means varies a repeat field detectioncondition of said repeat field detecting means corresponding to theanalyzed results of said analyzing means.
 11. The video data processingapparatus as set forth in claim 10, wherein said controlling meanscontrols the repeat field detecting condition of said repeat fielddetecting means in such a manner that the more the pattern of the repeatfield is continuous, the more the repeat field is easily detected andthat the more the pattern of the repeat field is discontinuous, the morethe repeat fields are uneasily detected.
 12. A video data processingapparatus for removing a repeat field from video data, comprising:repeat field detecting means for detecting the repeat field contained inthe video data; analyzing means for determining whether or not anoccurrence sequence of the repeat field contained in the video data isregular corresponding to the detected results of said repeat fielddetecting means; video data processing means for removing the repeatfield contained in the video data; and controlling means for controllingsaid video data processing means to remove a field determined as arepeat field by said repeat field detecting means from the video data ina period that the occurrence sequence of the repeat field is determinedregular by said analyzing means and for controlling said video dataprocessing means not to remove a field determined as a repeat field bysaid repeat field detecting means from the video data in a period thatthe occurrence sequence of the repeat field is determined irregular bysaid analyzing means.
 13. A video data processing apparatus forprocessing video data of which a first video material of which anoriginal material is processed with 2:3 pull-down process and a secondvideo material of an original material with a frequency of a normaltelevision signal coexist, comprising: analyzing means for analyzing arepetitive pattern of the repeat field contained in the video data anddetermining whether a current field of the video data is a field of thefirst video material or a field of the second video material; video dataprocessing means for removing the repeat field from the video data; andcontrolling means for controlling the operation of said video dataprocessing means corresponding to the analyzed results of said analyzingmeans.
 14. The video data processing apparatus as set forth in claim 13,wherein said controlling means controls said video data processing meansto remove a field determined as a repeat field by said repeat fielddetecting means from the video data when the current field of the videodata is determined as a field of the first video material, and whereinsaid controlling means controls said video data processing means not toremove a field determined as a repeat field by said repeat fielddetecting means when the current field of the video data is determinedas a field of the second video material.
 15. The video data processingapparatus as set forth in claim 14, further comprising: encoding meansfor encoding video data that is output from said video data processingmeans, wherein said controlling means controls an encoding mode of saidencoding means depending on the current field of the video data is afield of the first video material or a field of the second videomaterial.
 16. The video data processing apparatus as set forth in claim15, wherein said controlling means controls said encoding means toperform a prediction encoding process in a frame prediction mode-whenthe current field of the video data is determined as a field of thefirst video material; and wherein said controlling means controls saidencoding means to perform a prediction encoding process in a frameprediction mode or a field prediction mode when the current field of thevideo data is determined as a field of the second video material. 17.The video data processing apparatus as set forth in claim 15, whereinsaid controlling means controls said encoding means to perform aprediction encoding process in a frame prediction mode when the currentfield of the video data is determined as a field of the first videomaterial, and wherein said controlling means controls said encodingmeans to perform a prediction encoding process in one of a frameprediction mode and a field prediction mode whichever a smallergenerated bit amount when the current field of the video data isdetermined as a field of the second video material.
 18. The video dataprocessing apparatus as set forth in claim 15, wherein said controllingmeans controls said encoding means to perform a DCT process in a frameDCT mode when the current field of the video data is determined as afield of the first video material, and wherein said controlling meanscontrols said encoding means to perform a DCT process in one of a frameDCT mode and a field DCT mode when the current field of the video datais determined as a field of the second video material.
 19. The videodata processing apparatus as set forth in claim 15, wherein saidcontrolling means controls said encoding means to perform a DCT processin a frame DCT mode when the current field of the video data isdetermined as a field of the first video material, and wherein saidcontrolling means controls said encoding means to perform a DCT processin one of a frame DCT mode and a field DCT mode whichever a smallermotion compensation residual when the current field of the video data isdetermined as a field of the second video material.
 20. The video dataprocessing apparatus as set forth in claim 15, wherein said controllingmeans controls said encoding means to scan DCT coefficients in a zigzagscan mode when the current field of the video data is determined as afield of the first video material, and wherein said controlling meanscontrols said encoding means to scan DCT coefficients in an alternativescan mode when the current field of the video data is determined as afield of the second video material.
 21. The video data processingapparatus as set forth in claim 15, wherein said controlling meanscontrols said encoding means to perform a prediction encoding process ina frame prediction mode, perform a DCT process in a frame DCT mode, andscan DCT coefficients in a zigzag scan mode when the current field ofthe video data is determined as a field of the second video material,and wherein said controlling means controls said encoding means toperform a prediction encoding process in one of a frame prediction modeand a field prediction mode whichever a smaller generated bit amount,perform a DCT process in one of a frame DCT mode and a field DCT modewhichever a smaller motion compensation residual, and scan DCTcoefficients in a zigzag scan mode when the current field of the videodata is determined as a field of the second video material.
 22. A videodata processing apparatus for processing video data including aprogressive-scanned video material and an interlace-scanned videomaterial, comprising: analyzing means for analyzing the continuity of arepeat field contained in the video data and determining whether thecurrent field of the video data is a field of the progressive-scannedvideo material or a field of the interlace-scanned video material; videodata processing means for removing the repeat field from the video data;and controlling means for controlling said video data processing meansto remove a repeat field contained in the progressive-scanned videomaterial and not to remove a field contained in the interlace-scannedvideo material corresponding to the analyzed results of said repeatfield analyzing means.
 23. A video data processing method for removing arepeat field from video data, comprising the steps of: detecting therepeat field contained in the video data; analyzing a pattern of therepeat field contained in the video data corresponding to the detectedresults of the repeat field detecting step and determining whether thepattern of the repeat field is continuous or discontinuous; removing therepeat field contained in the video data; and controlling the video dataprocessing step to remove a field determined as a repeat field by therepeat field detecting step from the video data in a period that thepatten of the repeat field is determined continuous by the analyzingstep and the video data processing step not to remove a field determinedas a repeat field by the repeat field detecting step from the video datain a period that the pattern of the repeat field is determineddiscontinuous by the analyzing step.
 24. The video data processingmethod as set forth in claim 23, wherein the analyzing step is performedby determining that the pattern of the repeat field is continuous in aperiod of which predetermined patterns formed with a plurality of fieldsare regularly repeated, and wherein the analyzing step is performed bydetermining that the pattern of the repeat field is discontinuous in aperiod of which predetermined patterns formed with a plurality of fieldsare not regularly repeated.
 25. The video data processing method as setforth in claim 23, further comprising the step of: encoding video datathat is output from the video data processing step, wherein thecontrolling step is performed by controlling an encoding mode of theencoding step depending on whether the pattern is continuous ordiscontinuous.
 26. The video data processing method as set forth inclaim 25, wherein the controlling step is performed by controlling theencoding step to perform a prediction encoding process in a frameprediction mode in a period that the pattern is determined continuous,and wherein the controlling step is performed by controlling theencoding step to perform a prediction encoding process in one of a frameprediction mode and a field prediction mode in a period that the patternis determined discontinuous.
 27. The video data processing method as setforth in claim 25, wherein the controlling step is performed bycontrolling,the encoding step to perform a prediction encoding processin a frame prediction mode in a period that the pattern is determinedcontinuous, and wherein the controlling step is performed by controllingthe encoding step to perform a prediction encoding process in one of aframe prediction mode and a field prediction mode whichever a smallergenerated bit amount in a period that the pattern is determineddiscontinuous.
 28. The video data processing method as set forth inclaim 25, wherein the controlling step is performed by controlling theencoding step to perform a DCT process in a frame DCT mode in a periodthat the pattern is determined continuous, and wherein the controllingstep is performed by controlling the encoding step to perform a DCTprocess in one of a frame DCT mode and a field DCT mode in a period thatthe pattern is determined discontinuous.
 29. The video data processingmethod as set forth in claim 25, wherein the controlling step isperformed by controlling the encoding step to perform a DCT process in aframe DCT mode in a period that the pattern is determined continuous,and wherein the controlling step is performed by controlling theencoding step to perform a DCT process in one of a frame DCT mode and afield DCT mode whichever a smaller motion compensation residual in aperiod that the pattern is determined discontinuous.
 30. The video dataprocessing method as set forth in claim 25, wherein the controlling stepis performed by controlling the encoding step to scan DCT coefficientsin a zigzag scan mode in a period that the pattern is determinedcontinuous, and wherein the controlling step is performed by controllingthe encoding step to scan DCT coefficients in an alternate scan mode ina period that the pattern is determined discontinuous.
 31. The videodata processing method as set forth in claim 25, wherein the controllingstep is performed by controlling the encoding step to perform aprediction encoding process in a frame prediction mode, a DCT process ina frame DCT mode, and scan DCT coefficients in a zigzag scan mode in aperiod that the pattern is determined continuous, and wherein thecontrolling step is performed by controlling the encoding step toperform a prediction encoding process in one of a frame prediction modeand a field prediction mode whichever a smaller generated bit amount,perform a DCT process in one of a frame DCT mode and a field DCT modewhichever a smaller motion compensation residual, and scan DCTcoefficients in an alternate scan mode in a period that the pattern isdetermined discontinuous.
 32. The video data processing method as setforth in claim 23, wherein the controlling step is performed by varyinga repeat field detection condition of the repeat field detecting stepcorresponding to the analyzed results of the analyzing step.
 33. Thevideo data processing method as set forth in claim 23, wherein thecontrolling step is performed by controlling the repeat field detectingcondition of the repeat field detecting step in such a manner that themore the pattern of the repeat field is continuous, the more the repeatfield is easily detected and that the more the pattern of the repeatfield is discontinuous, the more the repeat fields are uneasilydetected.
 34. A video data processing method for removing a repeat fieldfrom video data, comprising the steps of: detecting the repeat fieldcontained in the video data; determining whether or not an occurrencesequence of the repeat field contained in the video data is regularcorresponding to the detected results of the repeat field detectingstep; removing the repeat field contained in the video data; andcontrolling the video data processing step to remove a field determinedas a repeat field by the repeat field detecting step from the video datain a period that the occurrence sequence of the repeat field isdetermined regular by the analyzing step and the video data processingstep not to remove a field determined as a repeat field by the repeatfield detecting step from the video data in a period that the occurrencesequence of the repeat field is determined irregular by the analyzingstep.
 35. A video data processing method for processing video data ofwhich a first video material of which an original material is processedwith 2:3 pull-down process and a second video material of an originalmaterial with a frequency of a normal television signal coexist,comprising the steps of: analyzing a repetitive pattern of the repeatfield contained in the video data and determining whether a currentfield of the video data is a field of the first video material or afield of the second video material; removing the repeat field from thevideo data; and controlling the operation of the video data processingmeans corresponding to the analyzed results of the analyzing step. 36.The video data processing method as set forth in claim 35, wherein thecontrolling step is performed by controlling the video data processingstep to remove a field determined as a repeat field by the repeat fielddetecting step from the video data when the current field of the videodata is determined as a field of the first video material, and whereinthe controlling step is performed by controlling the video dataprocessing step not to remove a field determined as a repeat field bythe repeat field detecting step when the current field of the video datais determined as a field of the second video material.
 37. The videodata processing method as set forth in claim 36, further comprising thestep of: encoding video data that is output from the video dataprocessing step, wherein the controlling step is performed bycontrolling an encoding mode of the encoding step depending on thecurrent field of the video data is a field of the first video materialor a field of the second video material.
 38. The video data processingmethod as set forth in claim 37, wherein the controlling step isperformed by controlling the encoding step to perform a predictionencoding process in a frame prediction mode when the current field ofthe video data is determined as a field of the first video material; andwherein the controlling step is performed by controlling the encodingstep to perform a prediction encoding process in a frame prediction modeor a field prediction mode when the current field of the video data isdetermined as a field of the second video material.
 39. The video dataprocessing method as set forth in claim 37, wherein the controlling stepis performed by controlling the encoding step to perform a predictionencoding process in a frame prediction mode when the current field ofthe video data is determined as a field of the first video material, andwherein the controlling step is performed by controlling the encodingstep to perform a prediction encoding process in one of a frameprediction mode and a field prediction mode whichever a smallergenerated bit amount when the current field of the video data isdetermined as a field of the second video material.
 40. The video dataprocessing method as set forth in claim 37, wherein the controlling stepis performed by controlling the encoding step to perform a DCT processin a frame DCT mode when the current field of the video data isdetermined as a field of the first video material, and wherein thecontrolling step is performed by controlling the encoding step toperform a DCT process in one of a frame DCT mode and a field DCT modewhen the current field of the video data is determined as a field of thesecond video material.
 41. The video data processing method as set forthin claim 37, wherein the controlling step is performed by controllingthe encoding step to perform a DCT process in a frame DCT mode when thecurrent field of the video data is determined as a field of the firstvideo material, and wherein the controlling step is performed bycontrolling the encoding step to perform a DCT process in one of a frameDCT mode and a field DCT mode whichever a smaller motion compensationresidual when the current field of the video data is determined as afield of the second video material.
 42. The video data processing methodas set forth in claim 37, wherein the controlling step is performed bycontrolling the encoding step to scan DCT coefficients in a zigzag scanmode when the current field of the video data is determined as a fieldof the first video material, and wherein the controlling step isperformed by controlling the encoding step to scan DCT coefficients inan alternative scan mode when the current field of the video data isdetermined as a field of the second video material.
 43. The video dataprocessing method as set forth in claim 37, wherein the controlling stepis performed by controlling the encoding step to perform a predictionencoding process in a frame prediction mode, perform a DCT process in aframe DCT mode, and scan DCT coefficients in a zigzag scan mode when thecurrent field of the video data is determined as a field of the secondvideo material, and wherein the controlling step is performed bycontrolling the encoding step to perform a prediction encoding processin one of a frame prediction mode and a field prediction mode whichevera smaller generated bit amount, perform a DCT process in one of a frameDCT mode and a field DCT mode whichever a smaller motion compensationresidual, and scan DCT coefficients in a zigzag scan mode when thecurrent field of the video data is determined as a field of the secondvideo material.
 44. A video data processing method for processing videodata field by field, a progressive-scanned video material and aninterlace-scanned video material coexisting in the video data,comprising the steps of: analyzing the continuity of a repeat fieldcontained in the video data and determining whether the current field ofthe video data is a field of the progressive-scanned video material or afield of the interlace-scanned video material; removing the repeat fieldfrom the video data; and controlling the video data processing step toremove a repeat field contained in the progressive-scanned videomaterial and not to remove a field contained in the interlace-scannedvideo material corresponding to the analyzed results of the repeat fieldanalyzing step.
 45. A video data encoding apparatus for encoding videodata in which a repeat field is placed in a predetermined sequence,comprising: analyzing means for analyzing a pattern of the repeat fieldcontained in the video data and determining whether or not the patternof the repeat field is continuous; video data processing means forremoving the repeat field from the video data; encoding means forencoding video data that is output from said video data processingmeans; and controlling means for controlling said video data processingmeans to remove a field determined as a repeat field by said repeatfield detecting means and perform an encoding process in a frameprediction mode and a frame DCT mode in a period that the pattern of therepeat field is determined continuous by said analyzing means and forcontrolling said video processing means not to remove a field determinedas a repeat field by said repeat field detecting means and perform anencoding process in one of a frame prediction mode and a fieldprediction mode and one of a frame DCT mode and a field DCT mode in aperiod that the pattern of the repeat field is determined discontinuousby said analyzing means.
 46. A video data encoding apparatus forencoding video data of which a first video material of which an originalmaterial is processed with 2:3 pull-down process and a second videomaterial of an original material with a frequency of a normal televisionsignal coexist, comprising: analyzing means for analyzing a repetitivepattern of the repeat field contained in the video data and determiningwhether the current field of the video data is a field of the firstvideo material or a field of the second video material; video dataprocessing means for removing the repeat field from the video data;encoding means for encoding video data that is output from said videodata processing means; and controlling means for controlling anoperation of said video data processing means and an encoding mode ofsaid encoding means corresponding to the analyzed results of saidanalyzing means.
 47. A video data encoding apparatus for encoding videodata of which a progressive-scanned video material and aninterlace-scanned video material coexist, comprising: analyzing meansfor analyzing the continuity of a repeat field contained in the videodata and determining whether the video data is the progressive-scannedvideo data or the interlace-scanned video data; video data processingmeans for removing the repeat field from the video data; encoding meansfor encoding video data that is output from said video data processingmeans; and controlling means for controlling said video data processingmeans to remove a repeat field contained in the progressive-scannedvideo material and not to remove a field contained in theinterlace-scanned video material corresponding to the analyzed resultsof said analyzing means and for controlling said encoding means toselect an encoding mode corresponding to the progressive-scanned videomaterial or the interlace-scanned video material.
 48. A video dataencoding apparatus for encoding video data of which aprogressive-scanned video material and an interlace-scanned videomaterial coexist, comprising: analyzing means for analyzing thecontinuity of a repeat field contained in the video data and determiningwhether the video data is the progressive-scanned video data or theinterlace-scanned video data; video data processing means for removingthe repeat field from the video data; encoding means for encoding videodata that is output from said video data processing means; andcontrolling means for controlling said video data processing means toremove a repeat field contained in the video data and said encodingmeans to perform an encoding process in an encoding mode correspondingto the progressive-scanned video material when the video data isdetermined as the progressive-scanned video material by said analyzingmeans and for controlling said video data processing means not to removea repeat field contained in the video data and said encoding means toperform an encoding process in an encoding mode corresponding to theinterlace-scanned video material when the video data is determined asthe interlace-scanned video material by said analyzing means.
 49. Avideo data encoding apparatus for encoding video data in which a repeatfield is placed, comprising: video data processing means for removingthe repeat field from the video data; encoding means for encoding videodata that has been processed by said video data processing means; andcontrolling means for analyzing the continuity of a repeat fieldcontained in the video data, determining whether a pattern of the repeatfield contained in the video data is continuous or discontinuous, andcontrolling an operation of said video data processing means and anencoding mode of said encoding means.
 50. A video data encodingapparatus for encoding video data in which a repeat field is placed,comprising: video data processing means for removing the repeat fieldfrom the video data; encoding means for encoding video data that hasbeen processed by said video data processing means; and controllingmeans for analyzing the continuity of a repeat field contained in thevideo data, determining whether an original material of the video datais a progress-scanned video material or interlace-scanned video data,and controlling an operation of said video data processing means and anencoding mode of said encoding means.
 51. A video data encoding methodfor encoding video data in which a repeat field is placed in apredetermined sequence, comprising the steps of: analyzing a pattern ofthe repeat field contained in the video data and determining whether ornot the pattern of the repeat field is continuous; removing the repeatfield from the video data; encoding video data that is output from thevideo data processing step; and controlling the video data processingstep to remove a field determined as a repeat field by the repeat fielddetecting step and perform an encoding process in a frame predictionmode and a frame DCT mode in a period that the pattern of the repeatfield is determined continuous by the analyzing step and for controllingthe video processing step not to remove a field determined as a repeatfield by the repeat field detecting step and perform an encoding processin one of a frame prediction mode and a field prediction mode and one ofa frame DCT mode and a field DCT mode in a period that the pattern ofthe repeat field is determined discontinuous by the analyzing step. 52.A video data encoding method for encoding video data of which a firstvideo material of which an original material is processed with 2:3pull-down process and a second video material of an original materialwith a frequency of a normal television signal coexist, comprising thesteps of: analyzing a repetitive pattern of the repeat field containedin the video data and determining whether the current field of the videodata is a field of the first video material or a field of the secondvideo material; removing the repeat field from the video data; encodingvideo data that is output from the video data processing step; andcontrolling an operation of the video data processing step and anencoding mode of the encoding step corresponding to the analyzed resultsof the analyzing step.
 53. A video data encoding method for encodingvideo data of which a progressive-scanned video material and aninterlace-scanned video material coexist, comprising the steps of:analyzing the continuity of a repeat field contained in the video dataand determining whether the video data is the progressive-scanned videodata or the interlace-scanned video data; removing the repeat field fromthe video data; encoding video data that is output from the video dataprocessing step; and controlling the video data processing step toremove a repeat field contained in the progressive-scanned videomaterial and not to remove a field contained in the interlace-scannedvideo material corresponding to the analyzed results of the analyzingstep and for controlling the encoding step to select an encoding modecorresponding to the progressive-scanned video material or theinterlace-scanned video material.
 54. A video data encoding method forencoding video data of which a progressive-scanned video material and aninterlace-scanned video material coexist, comprising the steps of:analyzing the continuity of a repeat field contained in the video dataand determining whether the video data is the progressive-scanned videodata or the interlace-scanned video data; removing the repeat field fromthe video data; encoding step for encoding video data-that is outputfrom the video data processing step; and controlling the video dataprocessing step to remove a repeat field contained in the video data andthe encoding step to perform an encoding process in an encoding modecorresponding to the progressive-scanned video material when the videodata is determined as the progressive-scanned video material by theanalyzing step and for controlling the video data processing step not toremove a repeat field contained in the video data and the encoding stepto perform an encoding process in an encoding mode corresponding to theinterlace-scanned video material when the video data is determined asthe interlace-scanned video material by the analyzing step.
 55. A videodata encoding method for encoding video data in which a repeat field isplaced, comprising the steps of: removing the repeat field from thevideo data; encoding video data that has been processed by the videodata processing step; and analyzing the continuity of a repeat fieldcontained in the video data, determining whether a pattern of the repeatfield contained in the video data is continuous or discontinuous, andcontrolling an operation of the video data processing step and anencoding mode of the encoding step.
 56. A video data encoding method forencoding video data in which a repeat field is placed, comprising thesteps of: removing the repeat field from the video data; encoding videodata that has been processed by the video data processing step; andanalyzing the continuity of a repeat field contained in the video data,determining whether an original material of-the video data is aprogress-scanned video material or interlace-scanned video data, andcontrolling an operation of the video data processing step and anencoding mode of the encoding step.